What is a Soft Bounce Email and Strategies to Resolve It Quickly

Email marketing is an uphill battle. You craft the perfect message, hit send, and then...crickets. You're not alone if you've silently cursed your fate, wondering why your email didn’t reach its target. If you’ve ever checked your inbox delivery report only to find that a whopping percentage of your emails have bounced or returned to sender, you know the panic that quickly sets in. What exactly does this mean? And, more importantly, how do I fix it? Understanding what a soft bounce email is and learning practical strategies to resolve it quickly can help improve your email deliverability and sender reputation.

Inframail’s email infrastructure can help you achieve your goals by providing valuable insights into your email performance and deliverability. This can help you identify bouncing emails, improve your email reputation, and boost your marketing performance.

What is a Soft Bounce Email, and How Does It Affect Deliverability?

an empty inbox - What Is a Soft Bounce Email

A soft bounce email, or a temporary email delivery failure, occurs when an email doesn’t reach its destination due to a problem on the recipient’s end. The server will make further attempts to deliver the email later. If the issue resolves itself, the sender won’t know there was a problem. Soft bounces happen when the recipient’s mailbox is full, either side hits some limits, or a message is too large to accept.

What Happens When Emails Bounce?

When an email is not delivered, the service provider (ESP) will return it to the sender. Often, the ESP includes a little note explaining why the delivery failed. The reasons a delivery might fail boil down to two categories: soft and hard bounces.

What is a Hard Bounce?

A hard bounce is a permanent failure of email delivery. It indicates that there will be no further attempt to deliver a message, and you must find a different way to reach the recipient. A hard-bounced email usually happens due to invalid email addresses typed in. Alternatively, a recipient’s ISP (Internet Service Provider) can reject your email for numerous reasons.

Causes of Hard Bounces

Hard bounces happen for many different permanent reasons. Here are the most common ones in more detail:

The Recipient Does Not Exist

This error indicates that the email address you used doesn’t exist. A simple typo could cause it, but maybe a nonexistent domain is the reason. Or maybe someone no longer works at a given company, and the recipient’s email address was removed–this would also cause a hard bounce.

If this is the reason for the bounce, double-check that you didn’t mistype your recipient’s address. Often, however, you can do nothing other than remove a recipient from the list. Keeping such contacts on your email list and having your emails bounce repeatedly will only affect your email deliverability. Negatively.

A Server Blocked Your Email

Modern mail servers reject tons of emails they suspect of being unwanted, causing deliverability issues and impacting your sender’s reputation. And while they’re almost always right to do so, sometimes the spam filters get rid of legitimate emails without hesitation. The reasons for this can be many.

A lack of proper authentication often plays a role, so ensure you have set up SPF, DKIM, and DMARC.
Check also if you have PTR Records set up and if they match
A record from your domain’s DNS.
Review Google and Yahoo’s new sender guidelines and ensure your sending practices align with all the requirements.

Improving Email Deliverability: List Management and Best Practices

To improve the experience of its users, ISPs also look at their past behavior when determining whether an email should be accepted or not. If you keep sending emails, but recipients never care to open them, a receiving server may finally reject them before they reach an inbox to save them the trouble.

For that reason, it’s good to clear your mailing lists occasionally and manually unsubscribe inactive contacts. If none helps and your emails bounce, it’s worth seeking support. If you experience problems with a particular domain, contacting them directly might get you whitelisted for future deliveries, improve your email deliverability, and reduce the chances of emails going to the spam folder.

Mailbox Is Full

Each mailbox has a specific data quota dedicated to outgoing and incoming emails. When the limit is reached, each new message will likely bounce once and for all. Some email service providers might give delivery another try a few days later, in which case this would fall into the soft bounce category.

But don’t hope for that. If you’re getting such alerts, try reaching the recipients another way. Maybe they’re not even aware of this fact. In many cases, unfortunately, this might indicate an abandoned account, so you’re better off searching for a different contact method anyway.

Challenge-Response Error

This error is slightly different from its predecessors on our list. Some people set up an additional firewall meant to authenticate senders. Sometimes, email providers set those up by default, too. When you email such a contact for the first time, you’ll get an automatic response. Usually, you’ll be asked to answer a question or perform some action to verify that you’re a legitimate sender.

Once you do, your email will be delivered. If you ignore this email and a few days pass, your email will bounce. The only thing you can do to avoid it is to complete the challenge satisfactorily. The good news is that in most cases, once you prove you’re a homo sapien, you won’t have to repeat this boring routine.

What is a Soft Bounce?

A soft bounce is a temporary email delivery failure. Although an email failed to deliver this time, a server will often make further attempts later. Sometimes, all you need to do is wait. An email bounces softly when the recipient’s mailbox is full, either side hits some limits, or an email message is deemed too large to be accepted.

Notifications for out-of-office or other autoresponders are sometimes treated as soft bounces, but they work differently. We’ll discuss those below. Some emails bounce for different reasons, and how clients communicate these errors is sometimes far from obvious.

Causes of Soft Bounces

Soft bounces also happen occasionally. Some are harmless, some indicate temporary problems, but many might foreshadow imminent hard bounces.

Here are the most common reasons behind soft bounces:

DNS Failure Or Other Errors

DNS Failure is a standard error caused by the receiving side. It indicates an issue with the Domain Name System; a message couldn’t be delivered then. The recipient’s email server was likely temporarily offline or misconfigured. If that is the case, delivery will likely be retried over the following days, and only if it fails multiple times will a hard bounce occur.

Sometimes, this error might also appear if the domain you send it to doesn’t exist. In such a case, there will be no future attempts, and you’ll need to look for other ways to contact a recipient. Any other errors can also occur during a transmission–for example, a connection may time out. In such a case, a server will likely retry several times before giving up.

A Message Is Too Large

Just as mailboxes have capacity limits, individual messages are also often subject to limitations. And while your outgoing servers allow some messages with large attachments, it may only sometimes be accurate for ISPs. If a message cannot be delivered due to its size, many ESPs will retry sending it over a specific period–usually several days. They’ll be permanently rejected if they fail to deliver by then.

Mailbox Storage Limits By Domain

Some ISPs might also limit the number of emails received to prevent spam from flooding recipients’ inboxes. While it’s rare for legitimate messages to be stopped like this, it might happen. In such cases, delivery will likely be retried several times, and only if none of the attempts succeed will the email bounce.

Autoresponder Is Triggered

Often, sending to a large group of recipients will result in a wave of autoresponders hitting your inbox. This is especially true during the holiday season. These messages often inform you that the recipient is currently out of the office and will get to your message a bit later. In such cases, the message has arrived in their inbox anyway, so there’s nothing you have to do.

It won’t hurt to follow up a few days after they’re back if you don’t hear from them until then. It’s worth reading through such autoresponders, however. Sometimes, they may inform you that someone you’re writing to has moved on to a different company and no longer reads these messages. Companies tend to keep such mailboxes alive and leave instructions on who to contact instead. If that’s the case, update the contacts on your mailing list.

Greylisting

Greylisting is a method some email servers use to block messages from unknown senders temporarily. When an email is greylisted, it is delayed and may need to be resent. This helps the email server check if the sender’s email server is legitimate and not spam.

Key Differences Between Soft vs. Hard Bounce

new email notification - What Is a Soft Bounce Email

Soft and hard bounces can hurt your email deliverability, but they differ greatly in their causes and implications. A soft bounce is temporary when an email is returned due to a full inbox or a server problem blocking delivery.

A hard bounce occurs when an email address has a permanent problem, such as being invalid or blocked. Email apps return hard bounces immediately, and no further attempts to deliver the email help.

How Do Soft Bounces and Hard Bounces Affect Your Sender’s Reputation?

Soft and hard bounces affect your sender’s reputation differently. Occasional soft bounces don’t hurt your sender’s reputation too much. If you notice repeated soft bounces to the same email address, that could indicate that the email address is problematic and should be removed from your list.

On the other hand, hard bounces can harm your sender’s reputation more because they signal that your list may contain invalid addresses. Regularly clearing out hard-bounced addresses helps improve deliverability.

What Should You Do About Soft Bounces and Hard Bounces?

There are different best practices for handling soft bounces versus hard bounces. For soft bounces, try resending the email at a later date. Use tools to track if the recipient’s inbox becomes available. For hard bounces, removing these addresses from your email list is best. This keeps your email bounce rates low and your campaigns effective.

How Do I Fix a Soft Bounce Email?

woman working on solutions - What Is a Soft Bounce Email

1. Keep Your Contact List in the Top Shape

A clean contact list helps reduce soft bounces. Invalid email addresses and outdated information can lead to email bounces.

How to do it:

Regularly check your contact list for invalid email addresses, typos, and inactive recipients.
Remove any emails that consistently bounce or show as inactive. This will improve your sender reputation and help more emails reach the inbox instead of bouncing back.

2. Use a Reliable Email Service Provider (ESP)

Choosing a dependable email service provider (ESP) helps ensure your emails are delivered successfully. A reliable ESP works with various email servers to ensure your messages aren’t lost or blocked.

How to do it:

Select an ESP known for good sender reputation and email deliverability.
Reliable ESPs often have features to manage bounce rates and offer insights into soft and hard bounces.
This support can help you monitor delivery issues and keep your sender reputation healthy.

3. Check Email Size and Attachment Limits

Email messages that are too large can be rejected by the recipient's email server, leading to a soft bounce. Large attachments or heavy media files can slow down the email delivery process.

How to Do It: Limit the size of attachments and avoid using large images in your emails. Compress images and avoid heavy files to keep your emails light and easy to load. Many email servers have size limits, so staying within these limits will help reduce soft bounces.

4. Avoid Spam Triggers

Spam filters look for specific words and patterns in email messages that might signal spam. If your email message is too large with many spam-like phrases or symbols, it might not reach the recipient’s inbox.

How to do it:

Avoid using all caps, excessive exclamation marks, or words like “free” or “urgent” too often in your email content.
Instead, keep your language natural and friendly.
Also, to show that your emails are legitimate, include a clear option to unsubscribe at the bottom of each one.

5. Respect Frequency Limits

Sending emails too often can lead to a higher bounce rate. If a recipient receives too many messages, their email server might block your emails or send them to the spam folder.

How to do it:

Limit your email frequency to a reasonable level.
Sending one or two emails weekly is often enough to keep your audience engaged without overwhelming them.
Test different schedules to see what works best for your audience.
This balance can improve deliverability rates and keep your email bounces low.

6. Authenticate Your Emails with SPF, DKIM, and DMARC

Authentication adds a layer of security to your emails, showing email servers that your messages are trustworthy. SPF, DKIM, and DMARC are tools that authenticate your emails to protect your sender’s reputation.

How to do it:

SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) ensure that only authorized email servers can send emails from your domain.
DMARC (Domain-based Message Authentication, Reporting & Conformance) helps you monitor and control authentication results.
Set up these records with your email service provider to strengthen email security and reduce bounces.

7. Keep an Eye on the Server Status

Sometimes, soft bounces happen because of issues with your email server. If your mail server is down or experiencing problems, your email may not get delivered.

How to do it:

Monitor your email server status regularly.
Many email service providers offer server status updates or alerts when there’s an issue. Staying informed means you can avoid sending emails when your server malfunctions.
This step can help keep your email bounce rates low and improve deliverability.

8. Verify Recipient Domain Health

Soft bounces can also occur if the recipient’s domain has issues. For example, your email might bounce back temporarily if the recipient’s server is down or has strict filtering rules.

How to do it:

Verify that the recipient’s domain is active and healthy before sending emails.
You can use online tools to check domain status and health.
If the recipient’s email server frequently causes issues, it might be best to remove that address from your list to protect your sender’s reputation.

9. Utilize a Consistent Sending Schedule

Consistently sending emails to new subscribers can improve your sender’s reputation. Irregular email patterns can sometimes cause email service providers to flag your messages as unusual, leading to soft bounces.

How to do it:

Plan a regular sending schedule that doesn’t overwhelm recipients. For example, sending weekly or bi-weekly updates works well for many audiences.
Stick to your chosen schedule so that recipients and email providers recognize your emails as consistent and reliable.

Start Buying Domains Now and Setup Your Email Infrastructure Today

Inframail is a cold email infrastructure provider that helps users boost their email deliverability with a solid technical foundation. The company’s automated system streamlines setting up and managing email infrastructure for cold email outreach.

With Inframail’s unlimited inboxes, users can avoid the deliverability roadblocks imposed by traditional email providers. Instead of wrestling with tech configurations, Inframail customers can focus on reaching more prospects.

What is a Soft Bounce Email, and How Does It Affect Deliverability?

A soft bounce email, or a temporary email delivery failure, occurs when an email doesn’t reach its destination due to a problem on the recipient’s end. The server will make further attempts to deliver the email later. If the issue resolves itself, the sender won’t know there was a problem. Soft bounces happen when the recipient’s mailbox is full, either side hits some limits, or a message is too large to accept.

What Happens When Emails Bounce?

When an email is not delivered, the service provider (ESP) will return it to the sender. Often, the ESP includes a little note explaining why the delivery failed. The reasons a delivery might fail boil down to two categories: soft and hard bounces.

What is a Hard Bounce?

A hard bounce is a permanent failure of email delivery. It indicates that there will be no further attempt to deliver a message, and you must find a different way to reach the recipient. A hard-bounced email usually happens due to invalid email addresses typed in. Alternatively, a recipient’s ISP (Internet Service Provider) can reject your email for numerous reasons.

Causes of Hard Bounces

Hard bounces happen for many different permanent reasons. Here are the most common ones in more detail:

The Recipient Does Not Exist

This error indicates that the email address you used doesn’t exist. A simple typo could cause it, but maybe a nonexistent domain is the reason. Or maybe someone no longer works at a given company, and the recipient’s email address was removed–this would also cause a hard bounce.

If this is the reason for the bounce, double-check that you didn’t mistype your recipient’s address. Often, however, you can do nothing other than remove a recipient from the list. Keeping such contacts on your email list and having your emails bounce repeatedly will only affect your email deliverability. Negatively.

A Server Blocked Your Email

Modern mail servers reject tons of emails they suspect of being unwanted, causing deliverability issues and impacting your sender’s reputation. And while they’re almost always right to do so, sometimes the spam filters get rid of legitimate emails without hesitation. The reasons for this can be many.

A lack of proper authentication often plays a role, so ensure you have set up SPF, DKIM, and DMARC.
Check also if you have PTR Records set up and if they match
A record from your domain’s DNS.
Review Google and Yahoo’s new sender guidelines and ensure your sending practices align with all the requirements.

Improving Email Deliverability: List Management and Best Practices

To improve the experience of its users, ISPs also look at their past behavior when determining whether an email should be accepted or not. If you keep sending emails, but recipients never care to open them, a receiving server may finally reject them before they reach an inbox to save them the trouble.

For that reason, it’s good to clear your mailing lists occasionally and manually unsubscribe inactive contacts. If none helps and your emails bounce, it’s worth seeking support. If you experience problems with a particular domain, contacting them directly might get you whitelisted for future deliveries, improve your email deliverability, and reduce the chances of emails going to the spam folder.

Mailbox Is Full

Each mailbox has a specific data quota dedicated to outgoing and incoming emails. When the limit is reached, each new message will likely bounce once and for all. Some email service providers might give delivery another try a few days later, in which case this would fall into the soft bounce category.

But don’t hope for that. If you’re getting such alerts, try reaching the recipients another way. Maybe they’re not even aware of this fact. In many cases, unfortunately, this might indicate an abandoned account, so you’re better off searching for a different contact method anyway.

Challenge-Response Error

This error is slightly different from its predecessors on our list. Some people set up an additional firewall meant to authenticate senders. Sometimes, email providers set those up by default, too. When you email such a contact for the first time, you’ll get an automatic response. Usually, you’ll be asked to answer a question or perform some action to verify that you’re a legitimate sender.

Once you do, your email will be delivered. If you ignore this email and a few days pass, your email will bounce. The only thing you can do to avoid it is to complete the challenge satisfactorily. The good news is that in most cases, once you prove you’re a homo sapien, you won’t have to repeat this boring routine.

What is a Soft Bounce?

A soft bounce is a temporary email delivery failure. Although an email failed to deliver this time, a server will often make further attempts later. Sometimes, all you need to do is wait. An email bounces softly when the recipient’s mailbox is full, either side hits some limits, or an email message is deemed too large to be accepted.

Notifications for out-of-office or other autoresponders are sometimes treated as soft bounces, but they work differently. We’ll discuss those below. Some emails bounce for different reasons, and how clients communicate these errors is sometimes far from obvious.

Causes of Soft Bounces

Soft bounces also happen occasionally. Some are harmless, some indicate temporary problems, but many might foreshadow imminent hard bounces.

Here are the most common reasons behind soft bounces:

DNS Failure Or Other Errors

DNS Failure is a standard error caused by the receiving side. It indicates an issue with the Domain Name System; a message couldn’t be delivered then. The recipient’s email server was likely temporarily offline or misconfigured. If that is the case, delivery will likely be retried over the following days, and only if it fails multiple times will a hard bounce occur.

Sometimes, this error might also appear if the domain you send it to doesn’t exist. In such a case, there will be no future attempts, and you’ll need to look for other ways to contact a recipient. Any other errors can also occur during a transmission–for example, a connection may time out. In such a case, a server will likely retry several times before giving up.

A Message Is Too Large

Just as mailboxes have capacity limits, individual messages are also often subject to limitations. And while your outgoing servers allow some messages with large attachments, it may only sometimes be accurate for ISPs. If a message cannot be delivered due to its size, many ESPs will retry sending it over a specific period–usually several days. They’ll be permanently rejected if they fail to deliver by then.

Mailbox Storage Limits By Domain

Some ISPs might also limit the number of emails received to prevent spam from flooding recipients’ inboxes. While it’s rare for legitimate messages to be stopped like this, it might happen. In such cases, delivery will likely be retried several times, and only if none of the attempts succeed will the email bounce.

Autoresponder Is Triggered

Often, sending to a large group of recipients will result in a wave of autoresponders hitting your inbox. This is especially true during the holiday season. These messages often inform you that the recipient is currently out of the office and will get to your message a bit later. In such cases, the message has arrived in their inbox anyway, so there’s nothing you have to do.

It won’t hurt to follow up a few days after they’re back if you don’t hear from them until then. It’s worth reading through such autoresponders, however. Sometimes, they may inform you that someone you’re writing to has moved on to a different company and no longer reads these messages. Companies tend to keep such mailboxes alive and leave instructions on who to contact instead. If that’s the case, update the contacts on your mailing list.

Greylisting

Greylisting is a method some email servers use to block messages from unknown senders temporarily. When an email is greylisted, it is delayed and may need to be resent. This helps the email server check if the sender’s email server is legitimate and not spam.

Key Differences Between Soft vs. Hard Bounce

Soft and hard bounces can hurt your email deliverability, but they differ greatly in their causes and implications. A soft bounce is temporary when an email is returned due to a full inbox or a server problem blocking delivery.

A hard bounce occurs when an email address has a permanent problem, such as being invalid or blocked. Email apps return hard bounces immediately, and no further attempts to deliver the email help.

How Do Soft Bounces and Hard Bounces Affect Your Sender’s Reputation?

Soft and hard bounces affect your sender’s reputation differently. Occasional soft bounces don’t hurt your sender’s reputation too much. If you notice repeated soft bounces to the same email address, that could indicate that the email address is problematic and should be removed from your list.

On the other hand, hard bounces can harm your sender’s reputation more because they signal that your list may contain invalid addresses. Regularly clearing out hard-bounced addresses helps improve deliverability.

What Should You Do About Soft Bounces and Hard Bounces?

There are different best practices for handling soft bounces versus hard bounces. For soft bounces, try resending the email at a later date. Use tools to track if the recipient’s inbox becomes available. For hard bounces, removing these addresses from your email list is best. This keeps your email bounce rates low and your campaigns effective.

How Do I Fix a Soft Bounce Email?

1. Keep Your Contact List in the Top Shape

A clean contact list helps reduce soft bounces. Invalid email addresses and outdated information can lead to email bounces.

How to do it:

Regularly check your contact list for invalid email addresses, typos, and inactive recipients.
Remove any emails that consistently bounce or show as inactive. This will improve your sender reputation and help more emails reach the inbox instead of bouncing back.

2. Use a Reliable Email Service Provider (ESP)

Choosing a dependable email service provider (ESP) helps ensure your emails are delivered successfully. A reliable ESP works with various email servers to ensure your messages aren’t lost or blocked.

How to do it:

Select an ESP known for good sender reputation and email deliverability.
Reliable ESPs often have features to manage bounce rates and offer insights into soft and hard bounces.
This support can help you monitor delivery issues and keep your sender reputation healthy.

3. Check Email Size and Attachment Limits

Email messages that are too large can be rejected by the recipient's email server, leading to a soft bounce. Large attachments or heavy media files can slow down the email delivery process.

How to Do It: Limit the size of attachments and avoid using large images in your emails. Compress images and avoid heavy files to keep your emails light and easy to load. Many email servers have size limits, so staying within these limits will help reduce soft bounces.

4. Avoid Spam Triggers

Spam filters look for specific words and patterns in email messages that might signal spam. If your email message is too large with many spam-like phrases or symbols, it might not reach the recipient’s inbox.

How to do it:

Avoid using all caps, excessive exclamation marks, or words like “free” or “urgent” too often in your email content.
Instead, keep your language natural and friendly.
Also, to show that your emails are legitimate, include a clear option to unsubscribe at the bottom of each one.

5. Respect Frequency Limits

Sending emails too often can lead to a higher bounce rate. If a recipient receives too many messages, their email server might block your emails or send them to the spam folder.

How to do it:

Limit your email frequency to a reasonable level.
Sending one or two emails weekly is often enough to keep your audience engaged without overwhelming them.
Test different schedules to see what works best for your audience.
This balance can improve deliverability rates and keep your email bounces low.

6. Authenticate Your Emails with SPF, DKIM, and DMARC

Authentication adds a layer of security to your emails, showing email servers that your messages are trustworthy. SPF, DKIM, and DMARC are tools that authenticate your emails to protect your sender’s reputation.

How to do it:

SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) ensure that only authorized email servers can send emails from your domain.
DMARC (Domain-based Message Authentication, Reporting & Conformance) helps you monitor and control authentication results.
Set up these records with your email service provider to strengthen email security and reduce bounces.

7. Keep an Eye on the Server Status

Sometimes, soft bounces happen because of issues with your email server. If your mail server is down or experiencing problems, your email may not get delivered.

How to do it:

Monitor your email server status regularly.
Many email service providers offer server status updates or alerts when there’s an issue. Staying informed means you can avoid sending emails when your server malfunctions.
This step can help keep your email bounce rates low and improve deliverability.

8. Verify Recipient Domain Health

Soft bounces can also occur if the recipient’s domain has issues. For example, your email might bounce back temporarily if the recipient’s server is down or has strict filtering rules.

How to do it:

Verify that the recipient’s domain is active and healthy before sending emails.
You can use online tools to check domain status and health.
If the recipient’s email server frequently causes issues, it might be best to remove that address from your list to protect your sender’s reputation.

9. Utilize a Consistent Sending Schedule

Consistently sending emails to new subscribers can improve your sender’s reputation. Irregular email patterns can sometimes cause email service providers to flag your messages as unusual, leading to soft bounces.

How to do it:

Plan a regular sending schedule that doesn’t overwhelm recipients. For example, sending weekly or bi-weekly updates works well for many audiences.
Stick to your chosen schedule so that recipients and email providers recognize your emails as consistent and reliable.

Start Buying Domains Now and Setup Your Email Infrastructure Today

Inframail is a cold email infrastructure provider that helps users boost their email deliverability with a solid technical foundation. The company’s automated system streamlines setting up and managing email infrastructure for cold email outreach.

With Inframail’s unlimited inboxes, users can avoid the deliverability roadblocks imposed by traditional email providers. Instead of wrestling with tech configurations, Inframail customers can focus on reaching more prospects.

What is a Soft Bounce Email, and How Does It Affect Deliverability?

A soft bounce email, or a temporary email delivery failure, occurs when an email doesn’t reach its destination due to a problem on the recipient’s end. The server will make further attempts to deliver the email later. If the issue resolves itself, the sender won’t know there was a problem. Soft bounces happen when the recipient’s mailbox is full, either side hits some limits, or a message is too large to accept.

What Happens When Emails Bounce?

When an email is not delivered, the service provider (ESP) will return it to the sender. Often, the ESP includes a little note explaining why the delivery failed. The reasons a delivery might fail boil down to two categories: soft and hard bounces.

What is a Hard Bounce?

A hard bounce is a permanent failure of email delivery. It indicates that there will be no further attempt to deliver a message, and you must find a different way to reach the recipient. A hard-bounced email usually happens due to invalid email addresses typed in. Alternatively, a recipient’s ISP (Internet Service Provider) can reject your email for numerous reasons.

Causes of Hard Bounces

Hard bounces happen for many different permanent reasons. Here are the most common ones in more detail:

The Recipient Does Not Exist

This error indicates that the email address you used doesn’t exist. A simple typo could cause it, but maybe a nonexistent domain is the reason. Or maybe someone no longer works at a given company, and the recipient’s email address was removed–this would also cause a hard bounce.

If this is the reason for the bounce, double-check that you didn’t mistype your recipient’s address. Often, however, you can do nothing other than remove a recipient from the list. Keeping such contacts on your email list and having your emails bounce repeatedly will only affect your email deliverability. Negatively.

A Server Blocked Your Email

Modern mail servers reject tons of emails they suspect of being unwanted, causing deliverability issues and impacting your sender’s reputation. And while they’re almost always right to do so, sometimes the spam filters get rid of legitimate emails without hesitation. The reasons for this can be many.

A lack of proper authentication often plays a role, so ensure you have set up SPF, DKIM, and DMARC.
Check also if you have PTR Records set up and if they match
A record from your domain’s DNS.
Review Google and Yahoo’s new sender guidelines and ensure your sending practices align with all the requirements.

Improving Email Deliverability: List Management and Best Practices

To improve the experience of its users, ISPs also look at their past behavior when determining whether an email should be accepted or not. If you keep sending emails, but recipients never care to open them, a receiving server may finally reject them before they reach an inbox to save them the trouble.

For that reason, it’s good to clear your mailing lists occasionally and manually unsubscribe inactive contacts. If none helps and your emails bounce, it’s worth seeking support. If you experience problems with a particular domain, contacting them directly might get you whitelisted for future deliveries, improve your email deliverability, and reduce the chances of emails going to the spam folder.

Mailbox Is Full

Each mailbox has a specific data quota dedicated to outgoing and incoming emails. When the limit is reached, each new message will likely bounce once and for all. Some email service providers might give delivery another try a few days later, in which case this would fall into the soft bounce category.

But don’t hope for that. If you’re getting such alerts, try reaching the recipients another way. Maybe they’re not even aware of this fact. In many cases, unfortunately, this might indicate an abandoned account, so you’re better off searching for a different contact method anyway.

Challenge-Response Error

This error is slightly different from its predecessors on our list. Some people set up an additional firewall meant to authenticate senders. Sometimes, email providers set those up by default, too. When you email such a contact for the first time, you’ll get an automatic response. Usually, you’ll be asked to answer a question or perform some action to verify that you’re a legitimate sender.

Once you do, your email will be delivered. If you ignore this email and a few days pass, your email will bounce. The only thing you can do to avoid it is to complete the challenge satisfactorily. The good news is that in most cases, once you prove you’re a homo sapien, you won’t have to repeat this boring routine.

What is a Soft Bounce?

A soft bounce is a temporary email delivery failure. Although an email failed to deliver this time, a server will often make further attempts later. Sometimes, all you need to do is wait. An email bounces softly when the recipient’s mailbox is full, either side hits some limits, or an email message is deemed too large to be accepted.

Notifications for out-of-office or other autoresponders are sometimes treated as soft bounces, but they work differently. We’ll discuss those below. Some emails bounce for different reasons, and how clients communicate these errors is sometimes far from obvious.

Causes of Soft Bounces

Soft bounces also happen occasionally. Some are harmless, some indicate temporary problems, but many might foreshadow imminent hard bounces.

Here are the most common reasons behind soft bounces:

DNS Failure Or Other Errors

DNS Failure is a standard error caused by the receiving side. It indicates an issue with the Domain Name System; a message couldn’t be delivered then. The recipient’s email server was likely temporarily offline or misconfigured. If that is the case, delivery will likely be retried over the following days, and only if it fails multiple times will a hard bounce occur.

Sometimes, this error might also appear if the domain you send it to doesn’t exist. In such a case, there will be no future attempts, and you’ll need to look for other ways to contact a recipient. Any other errors can also occur during a transmission–for example, a connection may time out. In such a case, a server will likely retry several times before giving up.

A Message Is Too Large

Just as mailboxes have capacity limits, individual messages are also often subject to limitations. And while your outgoing servers allow some messages with large attachments, it may only sometimes be accurate for ISPs. If a message cannot be delivered due to its size, many ESPs will retry sending it over a specific period–usually several days. They’ll be permanently rejected if they fail to deliver by then.

Mailbox Storage Limits By Domain

Some ISPs might also limit the number of emails received to prevent spam from flooding recipients’ inboxes. While it’s rare for legitimate messages to be stopped like this, it might happen. In such cases, delivery will likely be retried several times, and only if none of the attempts succeed will the email bounce.

Autoresponder Is Triggered

Often, sending to a large group of recipients will result in a wave of autoresponders hitting your inbox. This is especially true during the holiday season. These messages often inform you that the recipient is currently out of the office and will get to your message a bit later. In such cases, the message has arrived in their inbox anyway, so there’s nothing you have to do.

It won’t hurt to follow up a few days after they’re back if you don’t hear from them until then. It’s worth reading through such autoresponders, however. Sometimes, they may inform you that someone you’re writing to has moved on to a different company and no longer reads these messages. Companies tend to keep such mailboxes alive and leave instructions on who to contact instead. If that’s the case, update the contacts on your mailing list.

Greylisting

Greylisting is a method some email servers use to block messages from unknown senders temporarily. When an email is greylisted, it is delayed and may need to be resent. This helps the email server check if the sender’s email server is legitimate and not spam.

Key Differences Between Soft vs. Hard Bounce

Soft and hard bounces can hurt your email deliverability, but they differ greatly in their causes and implications. A soft bounce is temporary when an email is returned due to a full inbox or a server problem blocking delivery.

A hard bounce occurs when an email address has a permanent problem, such as being invalid or blocked. Email apps return hard bounces immediately, and no further attempts to deliver the email help.

How Do Soft Bounces and Hard Bounces Affect Your Sender’s Reputation?

Soft and hard bounces affect your sender’s reputation differently. Occasional soft bounces don’t hurt your sender’s reputation too much. If you notice repeated soft bounces to the same email address, that could indicate that the email address is problematic and should be removed from your list.

On the other hand, hard bounces can harm your sender’s reputation more because they signal that your list may contain invalid addresses. Regularly clearing out hard-bounced addresses helps improve deliverability.

What Should You Do About Soft Bounces and Hard Bounces?

There are different best practices for handling soft bounces versus hard bounces. For soft bounces, try resending the email at a later date. Use tools to track if the recipient’s inbox becomes available. For hard bounces, removing these addresses from your email list is best. This keeps your email bounce rates low and your campaigns effective.

How Do I Fix a Soft Bounce Email?

1. Keep Your Contact List in the Top Shape

A clean contact list helps reduce soft bounces. Invalid email addresses and outdated information can lead to email bounces.

How to do it:

Regularly check your contact list for invalid email addresses, typos, and inactive recipients.
Remove any emails that consistently bounce or show as inactive. This will improve your sender reputation and help more emails reach the inbox instead of bouncing back.

2. Use a Reliable Email Service Provider (ESP)

Choosing a dependable email service provider (ESP) helps ensure your emails are delivered successfully. A reliable ESP works with various email servers to ensure your messages aren’t lost or blocked.

How to do it:

Select an ESP known for good sender reputation and email deliverability.
Reliable ESPs often have features to manage bounce rates and offer insights into soft and hard bounces.
This support can help you monitor delivery issues and keep your sender reputation healthy.

3. Check Email Size and Attachment Limits

Email messages that are too large can be rejected by the recipient's email server, leading to a soft bounce. Large attachments or heavy media files can slow down the email delivery process.

How to Do It: Limit the size of attachments and avoid using large images in your emails. Compress images and avoid heavy files to keep your emails light and easy to load. Many email servers have size limits, so staying within these limits will help reduce soft bounces.

4. Avoid Spam Triggers

Spam filters look for specific words and patterns in email messages that might signal spam. If your email message is too large with many spam-like phrases or symbols, it might not reach the recipient’s inbox.

How to do it:

Avoid using all caps, excessive exclamation marks, or words like “free” or “urgent” too often in your email content.
Instead, keep your language natural and friendly.
Also, to show that your emails are legitimate, include a clear option to unsubscribe at the bottom of each one.

5. Respect Frequency Limits

Sending emails too often can lead to a higher bounce rate. If a recipient receives too many messages, their email server might block your emails or send them to the spam folder.

How to do it:

Limit your email frequency to a reasonable level.
Sending one or two emails weekly is often enough to keep your audience engaged without overwhelming them.
Test different schedules to see what works best for your audience.
This balance can improve deliverability rates and keep your email bounces low.

6. Authenticate Your Emails with SPF, DKIM, and DMARC

Authentication adds a layer of security to your emails, showing email servers that your messages are trustworthy. SPF, DKIM, and DMARC are tools that authenticate your emails to protect your sender’s reputation.

How to do it:

SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) ensure that only authorized email servers can send emails from your domain.
DMARC (Domain-based Message Authentication, Reporting & Conformance) helps you monitor and control authentication results.
Set up these records with your email service provider to strengthen email security and reduce bounces.

7. Keep an Eye on the Server Status

Sometimes, soft bounces happen because of issues with your email server. If your mail server is down or experiencing problems, your email may not get delivered.

How to do it:

Monitor your email server status regularly.
Many email service providers offer server status updates or alerts when there’s an issue. Staying informed means you can avoid sending emails when your server malfunctions.
This step can help keep your email bounce rates low and improve deliverability.

8. Verify Recipient Domain Health

Soft bounces can also occur if the recipient’s domain has issues. For example, your email might bounce back temporarily if the recipient’s server is down or has strict filtering rules.

How to do it:

Verify that the recipient’s domain is active and healthy before sending emails.
You can use online tools to check domain status and health.
If the recipient’s email server frequently causes issues, it might be best to remove that address from your list to protect your sender’s reputation.

9. Utilize a Consistent Sending Schedule

Consistently sending emails to new subscribers can improve your sender’s reputation. Irregular email patterns can sometimes cause email service providers to flag your messages as unusual, leading to soft bounces.

How to do it:

Plan a regular sending schedule that doesn’t overwhelm recipients. For example, sending weekly or bi-weekly updates works well for many audiences.
Stick to your chosen schedule so that recipients and email providers recognize your emails as consistent and reliable.

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What is a Soft Bounce Email and Strategies to Resolve It Quickly

What is a Soft Bounce Email and Strategies to Resolve It Quickly

What is a Soft Bounce Email and Strategies to Resolve It Quickly

Table of Contents

What is a Soft Bounce Email, and How Does It Affect Deliverability?

What Happens When Emails Bounce?

What is a Hard Bounce?

Causes of Hard Bounces

The Recipient Does Not Exist

A Server Blocked Your Email

Improving Email Deliverability: List Management and Best Practices

Mailbox Is Full

Challenge-Response Error

What is a Soft Bounce?

Causes of Soft Bounces

DNS Failure Or Other Errors

A Message Is Too Large

Mailbox Storage Limits By Domain

Autoresponder Is Triggered

Greylisting

Related Reading

Key Differences Between Soft vs. Hard Bounce

How Do Soft Bounces and Hard Bounces Affect Your Sender’s Reputation?

What Should You Do About Soft Bounces and Hard Bounces?

Related Reading

How Do I Fix a Soft Bounce Email?

1. Keep Your Contact List in the Top Shape

2. Use a Reliable Email Service Provider (ESP)

3. Check Email Size and Attachment Limits

4. Avoid Spam Triggers

5. Respect Frequency Limits

6. Authenticate Your Emails with SPF, DKIM, and DMARC

7. Keep an Eye on the Server Status

8. Verify Recipient Domain Health

9. Utilize a Consistent Sending Schedule

Start Buying Domains Now and Setup Your Email Infrastructure Today

Related Reading

Table of Contents

What is a Soft Bounce Email, and How Does It Affect Deliverability?

What Happens When Emails Bounce?

What is a Hard Bounce?

Causes of Hard Bounces

The Recipient Does Not Exist

A Server Blocked Your Email

Improving Email Deliverability: List Management and Best Practices

Mailbox Is Full

Challenge-Response Error

What is a Soft Bounce?

Causes of Soft Bounces

DNS Failure Or Other Errors

A Message Is Too Large

Mailbox Storage Limits By Domain

Autoresponder Is Triggered

Greylisting

Related Reading

Key Differences Between Soft vs. Hard Bounce

How Do Soft Bounces and Hard Bounces Affect Your Sender’s Reputation?

What Should You Do About Soft Bounces and Hard Bounces?

Related Reading

How Do I Fix a Soft Bounce Email?

1. Keep Your Contact List in the Top Shape

2. Use a Reliable Email Service Provider (ESP)

3. Check Email Size and Attachment Limits

4. Avoid Spam Triggers

5. Respect Frequency Limits

6. Authenticate Your Emails with SPF, DKIM, and DMARC

7. Keep an Eye on the Server Status

8. Verify Recipient Domain Health

9. Utilize a Consistent Sending Schedule

Start Buying Domains Now and Setup Your Email Infrastructure Today

Related Reading

Table of Contents

What is a Soft Bounce Email, and How Does It Affect Deliverability?

What Happens When Emails Bounce?

What is a Hard Bounce?

Causes of Hard Bounces

The Recipient Does Not Exist

A Server Blocked Your Email

Improving Email Deliverability: List Management and Best Practices

Mailbox Is Full