A List of Top SMTP Servers You Can Try For Free in 2023

Top Free SMTP Servers
Alex Kachalov Alex Kachalov 26 june 2023, 12:15 2473
For beginners

Running email campaigns is an integral part of any successful marketing strategy. Choosing the proper SMTP service provider to help you achieve this goal makes the process way easier. An ideal SMTP service will boost your email delivery rate, which is critical to the success of your email marketing. Your sales will suffer if you do not consistently reach your customers' inboxes. But how do you settle on the most appropriate service? Well, you don’t need to rely solely on ads or word of mouth — in fact, you can try out almost any SMTP service for free!

This article outlines the top free SMTP servers available for business owners who are looking for a decent SMTP service provider or just don’t need to send large volumes yet and seek to cut costs on their email marketing.

What is an SMTP Relay Server?

SMTP stands for Simple Mail Transfer Protocol. It is a set of rules that defines the framework for routing email messages through the internet. Besides carrying out the basic task, an SMTP relay server ensures that emails don't get mistaken for spam.

When offered as a service, SMTP relay servers specialize in sending transactional (such as password resets, delivery confirmations, etc.) or bulk emails. Companies usually require project-level functionalities to send large volumes of emails to their customers. And SMTP relay service providers can help them with this.

Why You May Need a Scalable SMTP Relay Server

Forwarding a few emails to your colleagues is simple and does not require any special tool. However, sending mass emails through your internet provider's email server can reduce delivery rates and even congest your bandwidth, negatively impacting your inbox placement rates.

As your company grows, you will eventually need to outsource to an SMTP relay service provider to handle the increasing volume of emails. It helps manage your email campaigns, allowing you to send large amounts of automated emails without disrupting your daily communications or domain and IP reputation. The best thing about these email management systems is that they are very robust and flexible, and you don't have to buy additional hardware or software.

The SMTP relay service is not to be mistaken with an email service provider (ESP). The latter offer additional tools for working with emails, such as constructors, templates, automatic chains, or more detailed analytics, but for a substantially higher price.

The SMTP server's sole responsibility is to deliver the message to the intended recipient (although certain additional functionality such as delivery, read and click tracking is usually provided). SMTP is the way to go when you need to send many letters quickly but don't need any list management functionality. Quite often, an SMTP service is offered as a part of a full-scale ESP service.

Free SMTP Server List

We've selected some of the widely used SMTP services with emphasis on dependency, affordability, and deliverability. All of them offer a free plan (either for a limited time or indefinitely) that may satisfy your testing needs or even provide a temporary solution while your business grows. However, as shown below, the terms of such free plans may differ vastly between various providers.


UniOne is one of the most reliable SMTP server providers

Unlike most other services on this list, every feature UniOne offers with paid plans is also available in the free plan — there are no limitations! With other services, you may have to pay lots of extra money for the same functionality. UniOne has a very decent deliverability speed — up to 60 million outgoing emails per hour with an ensured deliverability level.

You can send 6,000 emails free for the first 4 months. It costs a meager $6 per month to send 10,000 emails monthly with full functionality and, most importantly, 99.8% of your emails will arrive at their destination.

Learn more about UniOne SMTP here.

Free plan features

  • Free 6,000 emails per month for the first 4 months.
  • Excellent deliverability. The average deliverability level is 99.8%! The team monitors deliverability metrics in real-time, and you can order a dedicated IP address for even better results.
  • High security. Subscribers' private data is never stored on the sender's server.
  • No need for additional software. Any task you need may be performed using the API or right on your account page.
  • Detailed delivery and error reports. The complete event data, including the receiving server's responses, are provided using webhooks, allowing for detailed error analysis. The event logs are kept for up to 45 days.
  • An intuitive dashboard. You can see your email statistics, delivery rates, opens, click-throughs, and unsubscriptions.
  • UniOne consultation/recommendations. If you want to improve your results, you are free to ask UniOne for recommendations.
  • Versatility. Users can create sub-accounts and provide permission-based shared access.
  • 24/7 support. UniOne offers phone, chat and email support which is available 24 hours every day.
  • Customization and Personalization. You can customize and personalize your email to reach higher involvement rates.



Netcore (formerly Pepipost)

Netcore is a cloud-based SMTP email service

Netcore is a cloud-based SMTP email service aimed at high speed and reduced network latency. It allows bulk email sending by configuring an SMTP connection in regular email clients like Thunderbird, Outlook, or CRM applications. Users can connect their SMTP service to applications and software via the API. Netcore provides free 24/7 customer support. The company boasts using AI technology for innovative features such as predictive segmentation, better inboxing and subject line optimization.

Free plan features

  • 30,000 emails free for the first 30 days, then 100 emails daily.
  • Webhook integration for user behavior notification.
  • Allows creating sub-accounts and provides advanced email campaign analytics.
  • Ensures secure transmission and offers a 90-day history log.
  • Quick onboarding within minutes.
  • 24/7 live support.


SendGrid is a transactional and marketing email platform

SendGrid is a transactional and marketing email platform offering a cloud-based service that allows millions of customers to receive transactional and marketing emails. You don't need a server to send emails; just configure your email client settings using the SendGrid credentials. You can also use the pre-set SMTP configuration to implement the SMTP relay setup.

Unfortunately, Sendgrid's free plan restricts some essential features like email validation or sub-user management.

Free plan features

  • 100 emails daily;
  • APIs, SMTP Relay, and Webhooks;
  • Deliverability insights;
  • Delivery optimization tools;
  • Insightful analytics;
  • Ticket support (chat and phone support are available on paid plans);
  • Dynamic template editor.

Brevo (formerly SendinBlue)

Brevo's platform offers push notifications

In addition to its SMTP service, Brevo's platform offers push notifications, chat and SMS messaging and marketing automation. It helps optimize transactional emails and guarantees on-time delivery while granting access to a vast template gallery and a drag-and-drop message builder.

The free plan covers core API features and other functionalities like real-time email statistics, webhooks, and log retention. Sadly, it also lacks many features such as customer support, a landing page builder tool, A/B testing, send time optimization, and advanced open & click stats.

Free plan features

  • 300 emails per day;
  • Customizable email templates;
  • Drag & drop editor;
  • Shared inbox;
  • Transactional Emails;
  • SMS & WhatsApp Campaigns;
  • Email credits;
  • Dedicated IP.

Amazon SES

Amazon SES is another cloud-based email sending platform

Amazon SES (Simple Email Service) is another cloud-based email sending platform that helps digital marketers and application developers to send transactional and marketing emails via SMTP or API. This service is extremely scalable due to their "pay as you go" option. However, Amazon SES lacks some features like A/B testing and customizable dashboards.

Free plan features

  • 62,000 emails per month (for apps hosted in Amazon EC2 only);
  • Sender configuration options;
  • Flexible deployment options;
  • Sending statistics;
  • Sender Identity Management and Security;
  • Reputation and deliverability dashboards;
  • Mailbox simulator.


MailerSend is a transactional email management system

MailerSend is a transactional email management system for developers with a simple interface, allowing non-technical team members to contribute efficiently. MailerSend offers a fully customizable email builder with simple drag-and-drop capabilities.

Even though this service’s free plan offers a lot of great features as listed below, it doesn’t cover live chat support, split testing and a few other important features. It also adds a company logo to your emails.

Free plan features

  • 3000 free emails;
  • Email API, SMTP relay, webhooks;
  • Email campaign tracking and analytics;
  • Drag & drop builder;
  • HTML & rich text editor;
  • Bulk emailing;
  • 3 active templates;
  • 1 sending domain;
  • 1,000 daily API requests;
  • Email support (no live support).


SendPulse is an SMTP service and a multi-channel marketing platform

SendPulse is an SMTP service and a multi-channel marketing platform. It offers simple delivery solutions with user-friendly interfaces beneficial for marketers and developers. The free plan doesn't cover dynamic segmentation and A/B testing.

Free plan features

  • 12,000 emails per month (to up to 500 subscribers);
  • One landing page;
  • Three sender addresses and one domain;
  • 100MB free image storage capacity;
  • 100 email address verifications monthly.


Mandrill is a transactional email API with complete SMTP services

Mandrill is a transactional email API with complete SMTP services and analytics that ensures high email deliverability rates. Mandrill is now offered as a MailChimp add-on and is not available as a separate service. In other words, to try Mandrill you need to have a paid MailСhimp account in good standing. Overall, the demo feature is way too restrictive to be useful.

Free plan features

  • One-time package of 500 free emails to contacts on your verified domain only;
  • No click tracking;
  • Emails and sending history are kept for 30 days.


Postmark is a web-app transactional email service provider

Postmark is a web-app transactional email service provider. It focuses on delivering transactional emails rapidly and reliably by utilizing the closest available server. To maintain fast delivery, the service manually reviews each new account. The free plan offers full functionality, but the email quota may be insufficient for a proper test.

Free plan features

  • 100 emails per month forever;
  • Email API, SMTP relay, Webhooks;
  • Template engine;
  • Analytics;
  • Multiple Integrations.


Mailgun is an email automation service

Mailgun is an email automation service that provides free SMTP relays for developers. It offers robust APIs for sending, receiving, and tracking emails easily. It provides a cloud-based email solution and can send up to 250,000 emails per minute. Its free one-month trial includes 5,000 emails.

Free plan features

  • One month free trial period with 5,000 emails included;
  • Email APIs, SMTP Relay, and Webhooks;
  • Drag & drop template builder;
  • Suppression management;
  • 5 days of log retention;
  • Email tracking and analytics;
  • 24/7 ticket support.

Comparison table

  UniOne Brevo Postmark Mandrill Sendgrid Mailgun Netcore Amazon SES MailerSend SendPulse
Free emails limit 6,000 emails/ month for the first 4 months 300 emails/day 100 emails/month 500 emails one-time package 100 emails/day one-time package of 5,000 emails for 1 month 30 days of 30,000 free emails, then 100 per day forever 62,000 emails/month 3,000 free emails per month 12,000 emails/month (max 500 subscribers)
Free plan features                    
Live support Yes No No No No Yes Yes No Yes Yes
Send with API or SMTP relay Yes No Yes Yes Yes Yes Yes No Yes Yes
Email address validation Yes Yes No No No Yes Yes Yes Yes Yes
Dedicated IP Yes Yes No No No No Yes No No No
Customer support                    
Free support plans? Yes. Unione provides 24/7 customer support via email, phone, Whatsapp No. Premium and Enterprise customers get phone support. Email isn't an option. You must log in and create a ticket. Yes. Postmark provides customer support between 3am and 7pm EST, Monday to Friday via email, chat, or phone. No. Premium plans offer phone, chat, and email support. No. Support channels and response times vary by plan. Sendgrid's Personalized Support starts at $5,000/month for a Technical Account Manager. No. Chat is only available to customers on Growth plans (and above), and phone support is for Enterprise customers. Lower plans have email/ticket support only. Yes. Pepipost provides 24/7 customer support via email and chat No. SES plans lack customer support, which can be difficult for non-technical users. For support, buy an AWS support plan Yes. Email support on free plan. Priority email support, Live chat, Onboarding assistance on paid plans. Yes. 24/7 support via live chat
Free security features                    
SPF Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
DKIM Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
DMARC Yes Yes Yes No No No Yes Yes Yes Yes
Opportunistic TLS Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
Enforced TLS No No No No Yes Yes No No No No
2FA Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
Pricing model Payment amount depends on the number of emails sent. 3 paid plans with different features and send volumes Payment amount depends on the number of emails sent Emails are sold in 25k email blocks. The cost per block varies according to total email volume 3 paid plans with different features and send volumes 4 paid plans with different features and send volumes Payment amount depends on the number of emails sent Pricing by volume: $0.10 for every 1,000 emails you send Pricing by volume: $1 for every 1,000 emails you send. 4 paid plans with different features and send volumes
Cost of sending 10,000 emails $6/mo $25/mo (Lite plan) $10/mo $20 (+ Mailchimp subscription) $14.95/mo (Essentials plan) $8 (Flex plan) $1/mo $1/mo $10/mo $0/mo
Cost of sending 300,000 emails $150/mo $289/mo (Premium plan) $200/mo $240 (+Mailchimp subscription) $249/mo (Pro plan) $240/mo (Growth plan 250k emails + overages) $59.5/mo $30/mo $50/mo $55.88/mo
Cost of sending 1M emails $450/mo $599/mo (Premium plan) $535/mo $720 (+Mailchimp subscription) $449/mo (Pro Plan) $650/mo (Growth plan 1M emails) $171.5/mo $100/mo $340/mo $408/mo

Wrapping Up

With literally hundreds of SMTP service providers on the market, it is quite difficult to settle on a solution that fits your needs perfectly. Luckily, many of them offer free plans that you can use to evaluate the service. We have outlined a few notable SMTP services that you can try for free and provided some tips for you to make a smarter choice.

While most free plans have limited functionality, UniOne’s plan gives you everything you need right from the go. Our paid plans let you send more emails and achieve higher deliverability rates at very low prices.

Related Articles
For beginners
How to Send an SMTP Email Quick and Easy?
How to make and send emails through an SMTP personal server?
Yurii Bitko
18 january 2022, 23:395 min
For experts
What is Email Archiving? Solutions & How It Works
Billions of people around the world use email for business and everyday purposes. With this massive
Valeriia Dziubenko
12 january 2024, 14:229 min
For experts
What Is AMP for Email and How It Works?
Learn how AMP works from examples.
Alex Kachalov
03 may 2022, 11:508 min