Cold outreach can be challenging. You spend time crafting the perfect message to pique the recipient's interest, only to find it in the spam folder. Why does this happen? There are many reasons why emails fail to reach their destination, but one of the primary causes is email deliverability. Getting your emails to the right inbox is crucial for maximizing response rates and achieving your cold outreach goals. One of the best ways to improve email deliverability is by using the best SMTP server for your cold outreach campaigns. This article will explore the best SMTP servers on the market and how our cold email tips can help you achieve your cold outreach goals.

Inframail’s email infrastructure solution can help you achieve flawless email deliverability for your cold outreach campaigns, ensuring every message reaches the proper inbox and drives higher response rates.

Table of Contents

• What is an SMTP Server, and Why Do You Require One?

• 18 Best SMTP Servers for Fast and Secure Email Performance

• Start Buying Domains Now and Setup Your Email Infrastructure Today

What is an SMTP Server, and Why Do You Require One?

SMTP stands for Simple Mail Transfer Protocol. It is a communication protocol for sending and receiving email messages online. Mail servers and other message transfer agents (MTAs) use SMTP to send, receive, and relay mail messages. An SMTP or outgoing mail server is a computer or software that handles outgoing email messages. A mail server is a system that gathers, handles, and delivers email. An SMTP server is a mail server component that uses the Simple Mail Transfer Protocol (SMTP) to send outgoing mail. 

Understanding the Role of SMTP Servers

While the mail server handles incoming and outgoing emails, the SMTP server is concerned solely with sending and relaying outgoing emails to their appropriate destinations. It can also be referred to as an outgoing email server. SMTP providers use dedicated email servers to authenticate and reliably deliver your emails. These services send emails using proper authentication methods such as SPF, DKIM, and DMARC. These methods help identify your emails as legitimate, reducing their chances of being flagged as spam. Another benefit of SMTP providers is their detailed analytics and tracking features. You’ll have access to detailed logs showing your emails’ performance, including: 

• Delivery

• Bounce rates

• Open rates

How Does an SMTP Server Work?

Here's a breakdown of how it works: 

• Sending Emails: When you send an email, your client (like Gmail, Outlook, etc.) connects to an SMTP server. The server processes the email and determines the recipient’s email server. 

• Relaying Emails: If the recipient’s email server differs from the sender’s, the SMTP server relays the email to the appropriate server using the Domain Name System (DNS) to find the recipient’s IP address. 

• Receiving Emails: The recipient’s email server then receives the email and stores it until the recipient retrieves it using a different protocol, such as IMAP or POP3. SMTP servers ensure emails are delivered accurately and efficiently across the internet. Without them, email communication wouldn’t be possible.

Related Reading

• How to Send Bulk Emails
• Outreach Automation
• How to Know if Someone Opened Your Email
• How to Send a Cold Email for Networking
• How to Follow Up on a Cold Email
• Best Time to Send Cold Emails

18 Best SMTP Servers for Fast and Secure Email Performance

1. Inframail 

Inframail revolutionizes cold email infrastructure with unlimited inboxes at a single flat rate. With Microsoft-backed deliverability and dedicated IP addresses, we help scale their outreach efficiently: 

• Agencies

• Recruiters

• SDRs 

Main benefits of using our service: 

• Automated SPF, DKIM, and DMARC setup

• Dedicated email servers for each user

• 16-hour priority support daily

Unlike traditional providers that charge per inbox and leave you wrestling with technical configurations, Inframail streamlines the entire process. We handle the complex infrastructure setup while you focus on reaching more prospects. InfraMail provides a robust email infrastructure without the usual technical headaches and per-inbox costs, whether you're: 

• An agency looking to scale outreach

• A recruiter connecting with candidates

• An SDR driving sales

Start buying domains now and set up your email infrastructure today with our email infrastructure tool.

2. Google SMTP Server

Google’s free SMTP server is among the most popular options for sending their first transactional emails. All you need to access the service is a Gmail account. The company’s global infrastructure minimizes disruptions and favors simplicity and easiness. Google’s free SMTP service is reliable and offers excellent email deliverability for Gmail users, so your emails won’t be in the spam folder. 

Pros and Cons of Using Google SMTP for Free and Business Email Needs

Free emails: Google SMTP provides 500 emails per rolling 24 hours (for the 14 days of the free trial)

Best Features: 

• Send messages from a different email address and receive emails to your Gmail account. 

• For instance, if you have a business email address, you can add it as a custom domain name and send bulk emails through Gmail. 

• Great email deliverability. 

Pros: 

• Robust infrastructure that ensures reliability and uptime

• Easy integration

• Cost-effective tool for users with moderate email-sending needs. 

Cons: 

You must use your @gmail email address (for free Gmail SMTP)

Complicated setup. 

3. Amazon SES 

Amazon SES (Simple Email Service) is a cloud-based platform that provides users with a sophisticated SMTP interface. The SMTP service allows you to integrate Amazon with your email client, app, etc. Amazon SES lets you monitor your activity and reputation, an essential feature for every free SMTP relay server. Amazon SES is an incredible free SMTP option to get your work done quickly but it has limitations. 

Free emails: 

• The free tier offers 3,000 message charges/month (for the first 12 months). 

• A single email equals one message charge.

Best Features: 

• Excellent email deliverability with support for popular authentication methods like SPF, DKIM, and DMARC.

• Multiple sender configuration options (Amazon console, Amazon SES API).

• Reputation dashboard includes delivery rate, blocked domains, spam trap hits.

• Abundant free emails to get started. 

Pros: 

• Inexpensive solution with a lengthy free period.

• Robust security features. 

Cons: 

• Complex setup for specific functions.

• This SMTP server lacks deliverability insights. 

4. Moosend 

Moosend is one of the best email marketing automation platforms out there. When you sign up, the service offers sophisticated tools and responsive newsletter templates to scale your business. As it is natural, choosing Moosend’s SMTP is a no-brainer since it’s an ESP (Email Service Provider). The SMTP service is easy to use and lets you send order and account confirmations, invoices, and password reset messages. To start your email marketing journey, you can sign up here and enjoy the benefits of a premium yet cost-efficient service.

Free Emails: Unlimited in the 30-day free trial and all paid plans.

Best Features: 

• Powerful analytics and tracking system perfect for monitoring performance

• Excellent IP protection due to first-class infrastructure and IPs

• Effortless connection with WordPress sites. 

Pros: 

• All-in-one service ideal for high-volume senders

• Unlimited emails on its paid plan. 

Cons: 

You need to pay extra to customize your transactional messages. 

5. SMTP2GO 

SMTP2GO is a free SMTP relay server for sending emails, tracking them, and achieving an excellent deliverability rate. The service has an intelligent network with built-in redundancy to handle traffic and ensure your emails get delivered even in case of internet failure. Joining the free plan also grants you five days of premium email reporting. It only allows you to deliver ticket support to your recipients. 

Free emails: SMTP2GO’s free plan offers 1,000 emails per month.

Best Features: 

• Actionable real-time analytics to assist your email tracking efforts

• Spam-trap detection

• Easy-to-use API for developers and marketers

• 14 days of toll-free phone support and live chat to learn and configure the server. 

Pros: 

• Outstanding email deliverability

• The customer support team (live chat) is fast and effective. 

Cons: 

• Limited email reporting for free plan users

• Lacks automated options for managing bounced emails

• Customer support can only be reached via ticket in the free plan. 

6. Postmark 

Postmark’s free SMTP relay server promises to deliver transactional emails to your customers’ inboxes in a breeze. When you sign up, the software will equip you with sophisticated tools and responsive email templates to create mobile-friendly transactional campaigns. The email provider also gives you access to fast email delivery and detailed analytics to monitor your open and click-through rates. Postmark is a good SMTP server solution that’s secure, cost-efficient, and easy to integrate with your website or applications. 

Postmark: A Developer-Friendly SMTP Service for Secure and Fast Email Delivery

Free emails: Postmark’s free developer plan offers 100 emails/per month.

Best Features: 

• Lightning-fast email delivery

• Two-factor authentication (2FA) to keep your data secure

• Responsive, well-designed email templates

• 45 days of packed content history. 

Pros: 

• Easy integration with ActiveCampaign for robust automation

• Outstanding email deliverability. 

Cons: 

• Minimal free plan

• No list management and marketing automation features. 

7. SocketLabs 

SocketLabs is another free SMTP relay server that developers can use to deliver timely bulk emails to their recipients. The service is perfect for new developers and IT professionals who want high deliverability rates at no cost. Choosing SocketLabs’ hosted SMTP service will maximize your inbox placement and keep your emails away from spam folders. 

Free Emails: 40,000 emails

Best Features: 

• Email APIs allow you to integrate your statistics with in-house apps for better access;

• Fully-managed cloud SMTP servers

• Support for DKIM signing, SPF, and ISP traffic. 

Pros: 

• Advanced email analytics

• Personalized support (and consulting). 

Cons: 

• Limited free period

• Limited pre-built integrations. 

8. Mailgun 

Next in line is Mailgun, an SMTP service that sends automated transactional emails and tracks your email deliverability. Mailgun’s service is easy to integrate with any WordPress site or application and offers many features. You’ll get access to email address validation tools, inbox placement, and detailed documentation. As a developer-oriented email delivery service, it may lack some beginner-friendly features that specific Mailgun alternatives offer. 

Free Emails: 

• Mailgun’s free plan lets you send 100 emails daily. 

• The Foundation plan also has a 30-day free trial. 

Best Features: 

• Real-time email tracking and advanced analytics.

• Advanced deliverability features to reduce bounce rates and spam complaints.

• Simple connection with MBPs like Gmail, Yahoo, and Outlook (over TLS or SSL). 

Pros: 

• Email templates are available even in the free plan, and there are powerful email analytics. 

Cons: 

• Complex service for beginners.

• According to reviews, users experience customer service challenges. 

9. Brevo (formerly Sendinblue) 

Brevo is another great SMTP server solution with advanced email marketing capabilities. This free server is easy to use and has straightforward integration with WordPress, even for beginners. While the free plan doesn’t offer much, it’s ideal if you’re starting with transactional emails. The platform will also allow you to leverage other marketing channels, such as: 

• SMS marketing

• Live chats

• Ads

Free Emails: 300 free emails per day.

Best Features: 

• Flexible API to create custom and dynamic email messages

• Automated workflows with both email and SMS

• Effortless integration with services like WordPress, WooCommerce, Shopify, and Prestashop. 

Pros: 

• Wide range of plugins to integrate with WordPress, WooCommerce, Shopify, and CRM platforms

• All-in-one digital marketing platform to send both marketing and transactional emails.

Cons: 

• Deliverability isn’t as excellent as other solutions

• Pricing isn’t very flexible. 

10. Mailchimp Transactional Email 

Mailchimp Transactional Email (formerly Mandrill) is a paid Mailchimp add-on for your standard or higher account to deliver personalized transactional emails through an SMTP email server. While Mailchimp has no free plan, there’s a demo you can utilize to send automated emails. Mailchimp Transactional Email is an ideal SMTP solution for developers who want to increase their email delivery rate and customize sending. 

Free Emails: The Mailchimp Transactional demo offers 500 transactional emails to any email address on a verified domain (new users only).

Best Features: 

• Optimized delivery infrastructure

• Automatic loop registration

• Vast knowledge base with simple and informative guides. 

Pros: 

• It is ideal if you’re already using Mailchimp for your marketing campaigns

• Great analytics. 

Cons: 

The data retention limitations and the fact that it is not a standalone SMTP service (it requires a subscription to the email marketing platform). 

11. Sendgrid 

SendGrid is a marketing automation platform offering free and premium SMTP server functionality. With SendGrid, you can reliably deliver your transactional messages through the company’s global network. You are also equipped with powerful delivery optimization tools like custom DKIM and suppression management. SendGrid offers an excellent service for sending email messages despite being limited in the number of messages sent. 

Free Emails: This transactional email service gives you 100 daily emails.

Best Features: 

• Email testing for dynamic templates

• Easy integration and a straightforward setup flow to effectively start sending your transactional emails

• Developer-optimized SMTP relay. 

Pros: 

• Reliable infrastructure and excellent deliverability

• Comprehensive analytics. 

Cons: 

• Limited free plan email sending allowance

• Slow/expensive customer support.

12. MessageBird Email (formerly SparkPost) 

MessageBird acquired SparkPost, a heavy-duty SMTP server. It’s more of a B2B, email-for-email company software for large volumes of bulk emails.

MessageBird Email Pros: 

• Handles huge volumes: Probably the biggest bulk sender

• Reliability: Great uptime of 99.99%

• Trustworthy: Big names from many industries rely on its technology.
  
  

MessageBird Email Cons: 

• For big players only: Small businesses may feel underappreciated by a service that handles such large clients

• Too complex: As a tech-focused platform, it can be overwhelming for non-tech users; 

• Coding skills needed: You must code your emails without a drag-and-drop email editor. 

13. UniOne 

Both the free and paid plan users enjoy the complete set of features, including: 

• Versatile Web API

• Integration libraries for Ruby, PHP, and C#, SPF, DKIM, and DMARC authentications for both tracking and sender domains

• Click and unsubscribe from tracking

• Instant webhooks for event notification

• Template engines

• Email templates

• Up to 45 days of log retention

• Up to 400 days of analytics data storage

• 2FA

• GDPR Compliance

Maximizing Email Campaign Performance with UniOne's High Deliverability and Scalability

• Dedicated IP addresses: UniOne helps users build their independent sender reputation with optional dedicated IP addresses. 

• High deliverability rate: UniOne ensures 99.88% of all sent emails reach their destinations. 

• Seamless setup process: Users only need to configure the required connection settings and add a few DNS entries, which takes minutes to complete. 

• Comprehensive analytics features: An intuitive dashboard visualizes email campaign performance, tracks events in real-time, and facilitates convenient CSV data exports. 

• Impressive scalability: It integrates seamlessly into existing client systems and processes up to 60 million hourly emails. 

• 24/7 customer support: Support is available only through live chat and email, and the typical response time is less than 5 minutes. 

Addressing Limitations with UniOne: CSV Import Restrictions and Email Template Availability

• CSV import restrictions: While users are primarily happy with UniOne's CSV import functions, they believe UniOne could increase its maximum limit of 32 days. 

• Limited email templates: Some users have reported that they would like more than the 40+ email templates offered by UniOne. An increase to 170+ templates is announced for the next update. 

14. iDealSMTP 

Pros: 

• Reporting features: The platform offers a dashboard that tracks sent emails to monitor campaign performance. 

• Dedicated email server: Provides better control and security features for email marketing operations. 

• User-friendly interface: The platform makes setting up and managing email campaigns easy.
  
  

Cons: 

• Email deliverability issues: Although some users reported success with email deliverability, many others have complained about emails not reaching the intended recipients. 

• Limited responses to refund requests: In response to initial issues, some users have claimed that they couldn't get a refund after requesting one. 

• IP reputation concerns: There have been problems with the reputation of the assigned IP addresses for sending emails. 

15. Mailtrap 

Pros: 

• Strong Analytics and Alerts: The platform offers in-depth analytics and alert features that help users monitor email deliverability and performance effectively. 

• User-Friendly Experience: Many users find the interface intuitive and accessible, even for non-technical team members. 

• Responsive Customer Support: Users consistently highlight the support team’s helpfulness and quick responses, enhancing the overall experience.
  
  

Cons: 

• Domain Verification Speed: Reports suggest the speed of domain verification processes needs to be increased to improve user experience. 

• Limited Bulk Email Capabilities: Users note that Mailtrap is currently not equipped to handle peak volumes well, which could be a limitation for some businesses. 

• Need for More Integrations: Users want to see more ready-made integrations with popular CRMs and e-commerce platforms. 

16. SendPulse 

Your search ends here for those seeking email software that offers the most significant quantity of free emails. SendPulse, a Ukrainian company with a global presence, allows you to send up to 12,000 transactional emails every month for free via SMTP or API. They offer a comprehensive newsletter editor complete with email templates, free for up to 500 subscribers (and 15k emails). Classic email campaigns are also covered, making it great for email marketers. Suppose you have an affinity for the latest technology. In that case, you'll be delighted to know that SendPulse supports AMP for Email, which enables you to add interactive elements and forms to your mailing. 

Benefits of Using SendPulse 

• Highly generous free plan: Includes 12k emails every month 

• Complete marketing platform: Comes with a newsletter editor, CRM, email automation, chatbots, SMS, landing page editor, and more 

• Affordable paid plans: Even when you outgrow the free plan, the transition to a paid one won't hurt your pocket too much 

• Reporting: you can access the last 30 days of your analytics data
  
  

Drawbacks of Using SendPulse 

• Deliverability concerns: Average deliverability is only 74%, leading to many emails landing in spam or not being delivered. 

• Notably, issues primarily arose with AOL and Yahoo. 

17. Aha Send 

Aha Send is a transactional email service that stands out with its claim of faster email delivery than the competition. Like many others, it offers SMTP and a transactional email API. Our small-scale test (around 100 email addresses) couldn’t confirm its speed claim. The great thing about Aha Send is that it offers 1,000 free monthly emails. Even if you need to send more, it’s affordable: $5 per month for up to 10,000 emails and just $0.50 per 1,000 extra emails. 

Benefits of Using Aha Send 

• Free plan: Send up to 1,000 emails monthly for free. 

• Easy-to-use interface: Setup is quick and simple, and you can add team members to your account at no extra cost. 

Drawbacks of using Aha Send 

• New kid on the block: There’s not much information available about Aha Send besides its origin in Austria. LinkedIn shows the founder as the only employee. 

• Deliverability rate: In our limited tests, Aha Send had a similar deliverability rate to Brevo, which puts them in the middle of our deliverability rating table. 

18. Elastic Email 

Operating from Poland, this email service provider offers two primary services: 

• Their Email API 

• Email Marketing tool

If you're in the market for a transactional email provider, their Email API product, which includes a free SMTP server, might pique your interest. The free plan is very restrictive, with a limit of 100 emails per day. This limitation becomes more significant given that their email deliverability rate was the poorest among all the providers I tested. According to their support, this is due to the shared IP addresses in their free accounts. It's essential to remember this if you're considering their free plan. 

Benefits of Using Elastic Email 

• Cheap Prices: Yes, their prices are low. I don’t know the value. 

• Live chat support: Thankfully, I had a very patient support staff who helped with the setup. 

Drawbacks of Using Elastic Email 

• Poor deliverability: They had the lowest scores of all the providers—Outlook, Yahoo, and AOL sent our messages to the spam folder. When I talked to support about it, they explained that free users only get a shared IP address, which seems to be responsible for the poor results due to its sender reputation. Like other services like SMTP2GO, even free plans can achieve top email deliverability rates.

Related Reading

• How Many Cold Emails Per Day
• Mailchimp for Cold Emails
• SMTP Send Email
• Best Bulk Email Sender
• Best Email Outreach Tools
• Bulk Email Providers
• Best Business Email Providers
• AI Tools for Email Marketing
• Amazon Ses Alternatives
• Postfix vs Sendmail
• Amazon Ses vs Sendgrid

Start Buying Domains Now and Setup Your Email Infrastructure Today

Cold emailing can be a daunting task, but Inframail makes it easy. At Inframail, we are revolutionizing cold email infrastructure with unlimited inboxes at a flat rate. We provide: 

• Microsoft-backed deliverability

• Dedicated IP addresses

• Automated technical setup 

We help scale their outreach efficiently: 

• Agencies

• Recruiters

• SDRs 

Simplifying Email Deliverability with Dedicated Servers and Automated Security Setup

With Inframails email infrastructure, you can rest assured that your emails will reach your prospects' inboxes instead of their spam folders. 

Our service offers: 

• Automated SPF, DKIM, and DMARC setup

• Dedicated email servers for each user

• 16-hour priority support daily

Unlike traditional providers that charge per inbox and leave you wrestling with technical configurations, Inframail streamlines the entire process. We handle the complex infrastructure setup while you focus on reaching more prospects. 

Say Goodbye to Technical Headaches

Whether you're an agency looking to scale outreach, a recruiter connecting with candidates, or an SDR driving sales, Inframail provides a robust email infrastructure without the usual technical headaches and per-inbox costs. Start buying domains now and set up your email infrastructure today with our email infrastructure tool.

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