10 Best Free SMTP Servers for Reliable Email Delivery in 2025

Sending transactional emails shouldn’t cost a fortune—especially when you’re just getting started. Password resets, order confirmations, and welcome emails need to reach inboxes reliably, sure. But paying enterprise extravagant prices for a handful of daily sends? That makes little sense. 

The good news is that several excellent SMTP servers offer generous free tiers that handle thousands of emails monthly without charging a cent.

I’ve tested dozens of SMTP service providers to find the ones that actually deliver on their promises. Some excel at developer tools, others prioritize deliverability, and a few bundle marketing features you might find useful down the road. Without further ado, let’s check them out.

How SMTP Servers Work

SMTP (Simple Mail Transfer Protocol) is the standard for sending emails across the internet. When you hit send, your email client connects to an SMTP server, which routes your message through a series of mail transfer agents until it reaches the recipient’s inbox. The protocol handles authentication, encryption, and delivery confirmation behind the scenes.

For transactional emails—automated messages triggered by user actions—you typically connect your application to an SMTP server using credentials provided by your email service. Your app sends messages via SMTP commands, and the email server handles deliverability, bounce management, and sender reputation monitoring. Most providers also offer API alternatives that skip SMTP entirely, sending emails via HTTP requests instead.

Free SMTP email servers give you access to this infrastructure without upfront costs. They maintain IP address reputation, handle authentication protocols like SPF and DKIM, and provide delivery analytics. The trade-off is volume limits and occasionally reduced support, but for many use cases, free tiers are more than sufficient.

Best Free SMTP Servers at a Glance

SMTP Provider	Free Plan	Starting Price
Sender	15,000 emails/mo + 2,500 contacts	$7/month
SMTP2GO	1,000 emails/mo	$15/month
SendPulse	15,000 emails/mo	$6/month
Mailtrap	4,000 emails/mo	$15/month
MailerSend	500 emails/mo	$6/month
Postmark	100 emails/mo	$15/month
Brevo	300 emails/day	$10/month
Gmail SMTP	500/day	Free
SendGrid	60 Free trial only	$20/month
Amazon SES	$200 USD in credits	$0.10 per 1k

What to Consider When Choosing a Free SMTP Server

Choosing a sturdy—and more importantly, free—SMTP server is no walk in the park. There’s a lot to weigh up, from deliverability and limits to reliability and their support team, not to mention hidden usage caps. 

That said, here are the key areas you should consider before putting all your chips on the chosen SMTP server:

• Deliverability Rate. The best SMTP server means nothing if emails land in spam. Look for providers with strong IP reputation, SPF/DKIM/DMARC support, and proven inbox placement rates. Established providers invest in email deliverability—newer or cheaper options often struggle here.
• Email Volume Limits. Free tiers cap sends daily, monthly, or both. Calculate your actual needs before choosing—a 100 daily limit won’t work if you send 500 password resets on busy days. Watch for subscriber limits too, not just email counts.
• Ease of Setup and Integration. Some providers take minutes to configure, others require technical expertise. Check documentation quality, available SDKs for your programming language, and whether SMTP credentials are straightforward to generate. Complex setup wastes development time.
• Security Features. Ensure TLS encryption is standard, not optional. SMTP authentication should be mandatory to prevent unauthorized use. Look for two-factor authentication on dashboards and API key management for production applications.
• Analytics and Tracking. Tracking deliveries, opens, bounces, and clicks helps identify problems fast. Free tiers often limit log retention or hide detailed analytics. Verify you can access enough data to troubleshoot delivery issues effectively.

10 Best Free SMTP Servers Reviewed

Here’s your go-to breakdown of each provider’s features, strengths, and limitations to help you choose confidently.

Sender — Best SMTP Service for Small Businesses

Sender punches above its weight with one of the most generous free tiers available. The platform combines SMTP relay service with a drag-and-drop email builder, making it equally useful for transactional and email marketing messages. 

I found the setup process straightforward—DNS authentication took minutes, and test emails landed in inboxes immediately.

The dashboard, then, provides solid analytics without overwhelming you with data. You see deliveries, opens, clicks, and bounces at a glance. For small businesses juggling multiple priorities, this simplicity is refreshing compared to developer-focused tools with steep learning curves.

Key Features

• SMTP relay and REST API access;
• Drag-and-drop email builder;
• Automated email sequences;
• Real-time analytics dashboard;
• SPF, DKIM, and DMARC support.

Pros & Cons

Pricing

Paid plans start at $7/month for 30,000 emails and remove branding. Sender’s generous free plan includes 15,000 emails monthly for up to 2,500 subscribers. 

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SMTP2GO — Excellent Deliverability and Team Collaboration

SMTP2GO focuses heavily on deliverability and team features. The platform offers detailed reporting that shows exactly where your emails end up—inbox, spam folder, or bounced. Their reputation monitoring alerts you to potential issues before they tank your sender score.

What sets SMTP2GO apart is the collaboration functionality. Multiple team members can access the dashboard with role-based permissions, making it ideal for agencies or businesses with dedicated email operations staff. The free tier is modest but sufficient for testing and low-volume transactional sends.

Key Features

• Real-time deliverability reporting;
• Team collaboration with user roles;
• Email archiving and searchable logs;
• Dedicated IP options on paid plans;
• 24/7 support even on free tier.

Limitations

• Limited email volume. You can only send 1,000 emails per month on the free plan;
• Daily sending cap. There is a 200 emails/day limit, which may not be enough for higher-volume needs;
• Hourly restrictions. If you haven’t verified a sender domain, the limit drops to 25 emails per hour;
• Limited reporting. The free plan only retains 5 days of activity history (opens, bounces, clicks);
• Limited collaboration. Only 2 users are allowed on the free plan, restricting team access.

Pros & Cons

Pricing

Paid plans begin at $15/month for 10,000 emails. Free plan available for up to 1,000 email sends per month.

“We have deployed SMTP2Go as our SMTP relay for some custom in-house applications. The setup and management is very easy and straightforward and it provide enough granularity in configuration to meet our business and regulatory needs. We really enjoy the account configuration which you can specify different disclaimer and archiving (Compliance BCC ) for each account to meet different requirements for each business unit.”

— User’s review on G2

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SendPulse — High Volume Sending with Marketing Tools

SendPulse offers an impressive 15,000 free emails monthly, matching Sender’s generous allowance. The platform bundles SMTP relay with chatbots, web push notifications, and SMS—useful if you’re building a multi-channel communication strategy.

The SMTP service itself is reliable, with solid deliverability across major providers. I appreciated the detailed statistics showing delivery rates by domain, which helped identify potential issues with specific email service providers. The interface leans busy, cramming lots of features into tight spaces.

Key Features

• SMTP relay with detailed domain statistics;
• Multi-channel messaging (email, SMS, push);
• Email verification tool included;
• Automation workflows;
• A/B testing on subject lines.

Limitations

• Daily sending cap. The free SMTP plan limits you to 400 emails per day, SendPulse which can be restrictive for transactional-heavy applications;
• Limited sender addresses. You can only add up to 2 email addresses (not domains) as a sender SendPulse on the free plan, limiting flexibility for multi-brand setups;
• Low subscriber limit. The free plan includes up to 500 subscribers, which fills up quickly as your list grows;

Pros & Cons

Pricing

Paid plans start at $6/month and remove restrictions. Free plan available, which includes 15,000 emails for up to 500 subscribers.

“Honestly, SendPulse has become my number one email marketing software after trying several others. One of the key reasons why I like SendPulse is their drag-and-drop editor. Even people with no experience are able to navigate their way around easily. I have integrated their service to a lot of my clients, and it’s really exciting.”

— Stuart’s review on G2

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Mailtrap — Developers and Email Testing

Mailtrap stands out by solving a specific problem: testing emails without spamming real inboxes. The platform captures outgoing emails in a sandbox environment, letting you inspect HTML rendering, spam scores, and headers before going live.

Beyond testing, Mailtrap offers production SMTP sending through their email API. One of its standout features, however, is the email testing infrastructure. This feature allows users to capture and inspect emails sent during development and testing phases without actually sending them to real inboxes. Put it simply, this feature is invaluable for debugging and fine-tuning email content before going live.

The free tier is limited but sufficient for small projects. The real value is the testing infrastructure—something most competitors lack entirely.

Key Features

• Email sandbox for safe testing;
• HTML/CSS rendering previews;
• Spam score analysis;
• Production SMTP and API sending;
• Team inboxes for collaboration.

Limitations

• Low email quota. The free plan only allows sending 3,000 emails/month, which is restrictive for larger projects;
• Daily sending limit. You are capped at ≈150 emails/day;
• Limited contacts. The free plan restricts you to just 100 contacts, limiting your reach;
• Single user/domain. Only 1 user and 1 domain are allowed on the free plan, restricting team collaboration and multiple sender domains.

Pros & Cons

Pricing

Paid plans start at $15/month for 10,000 emails. Free plan includes 4,000 emails monthly.

“Mailtrap’s email sandbox feature solved a problem we have had for years – how to trap and review emails being generated by our DEV and UAT environments and preventing them filling our inboxes. It also allowed our team the convenience of reviewing the emails in a single place. Now we can’t do without it! Next we are planning to move to their email API as the competitor we are currently using hasn’t innovated for years.”

— Seth’s review on G2

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MailerSend — Flexible Daily Sending Without Caps

MailerSend, built by the MailerLite, offers a developer-friendly SMTP service with generous limits. The 3,000 monthly emails don’t have daily caps, meaning you can send in bursts when needed. This flexibility is rare among free tiers.

MailerSend offers a smooth integration process through its well-documented API and SMTP relay, making setup easy for developers. Its analytics are thorough yet accessible, providing key insights without overwhelming users. 

Meanwhile, the email template builder excels at creating transactional email designs, offering flexibility and customization options to ensure emails are on-brand and effective. 

Overall, MailerSend balances ease of use with robust functionality, making it ideal for both technical and non-technical users alike.

Key Features

• SMTP relay and REST API;
• No daily sending limits;
• Drag-and-drop template builder;
• Inbound email routing;
• SMS messaging available.

Limitations

• Very low email quota. The free plan allows only 500 emails/month, which is limiting for many users;
• Strict usage limits. You’re capped at 100 requests/day, with only 1 webhook, 1 API token, and 1 domain allowed;
• Limited concurrent connections. The free plan allows only 5 concurrent SMTP connections, restricting high-volume sending;
• Single user restriction. Only 1 user is allowed on the free plan, limiting team collaboration.

Pros & Cons

Pricing

Paid plans start at $6/month. Free forever plan includes 500 emails monthly. 

“I have been using MailerSend for a year now for sending transactional emails on a couple of websites. It was very easy to integrate using our stack which is Laravel. A few days ago we had a problem with a form that was also sending an email and was used for spamming, the team was very responsive, helpful and guided me to correct the problem and unlock our account.”

— Catalin’s review on G2

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Postmark — Premium Transactional Email Delivery

Postmark positions itself as a premium option focused exclusively on getting transactional email delivered. They refuse to send marketing messages, which keeps their IP reputation pristine. The result is reliable deliverability—emails consistently land in primary inboxes rather than promotions tabs.

The free tier is minimal at 100 emails monthly, but it’s enough to test their infrastructure. If transactional email deliverability is a priority and the budget allows, Postmark becomes a solid choice. It provides globally distributed SMTP endpoints, ensuring low-latency sending and fast delivery. 

Postmark also supports custom metadata and tagging in SMTP headers, helping you track and categorize emails efficiently. 

Key Features

• Transactional-only focus;
• Industry-leading deliverability rates;
• Message streams for organization;
• Detailed delivery analytics;
• 45-day searchable message retention.

Limitations

• Very small free plan quota. The free plan allows only 100 emails per month, which is suitable for testing but not for production use;
• Not designed for marketing emails. Postmark focuses on transactional emails (e.g., password resets, notifications), lacking features for marketing emails, bulk campaigns, or list management;
• Basic email design tools. No drag-and-drop builder or advanced email templates for creating visually rich marketing emails;
• Higher costs at scale. The cost per email increases as your volume grows, making it expensive for high-volume sending compared to some other providers;
• Limited CRM and marketing features. Lacks integrated tools for customer relationship management, segmentation, and marketing automation — you’d need additional tools for those purposes.

Pros & Cons

Pricing

Paid plans start at $15/month for 10,000 emails. Free developer plan includes 100 emails monthly. 

“I’ve started recommending my clients Postmark after trying a lot of email providers. Postmark is a small company yet one of the best in the transactional email world! The setup process, stats for emails and user interface are minimal yet do a great job. It has plugins for WordPress which uses API to send emails rather than SMTP connections. This way they are able to deliver super fast email service.”

— Vikas’ review on G2

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Brevo — All-in-One Marketing Suite with CRM

Brevo (formerly Sendinblue) bundles SMTP relay with a full marketing suite including CRM, landing pages, and chat. The 300 daily email limit translates to roughly 9,000 monthly—competitive for a platform offering this much functionality.

The SMTP service works reliably, though setup requires navigating a feature-heavy dashboard. For businesses wanting transactional email service alongside marketing tools without managing multiple platforms, Brevo consolidates everything.

For instance, this email marketing platform supports webhooks for tracking events like email deliveries, opens, and bounces, which is useful for monitoring email performance in real-time. Meanwhile, with geographically distributed SMTP relays, Brevo optimizes email delivery by connecting users to the best-performing server based on their location.

Key Features

• SMTP relay and marketing automation;
• Built-in CRM system;
• Transactional and marketing in one platform;
• Landing page builder;
• Chat and SMS channels.

Limitations

• Daily sending limit. The free plan allows only 300 emails/day, which limits how many emails you can send at once (around 9,000 per month);
• Brevo branding. Emails sent from the free plan will include Brevo’s branding (footer), which may not look professional for businesses;
• Limited automation. The free plan allows automation for up to 2,000 contacts only. If you exceed that, you can’t add more contacts to automation workflows;
• Only 1 user. The free plan is limited to 1 user; team collaboration and multiple user access require upgrading to a paid plan.

Pros & Cons

Pricing

Paid plans start at $10/month for 5,000 monthly emails and remove daily limits. Free plan allows 300 emails daily with unlimited contacts. 

“I like Brevo because its API works well and is easy to test with for emails and integrations. Making and scheduling campaigns is simple, so I can quickly check that everything works as expected. The automation setups are easy to follow, which helps when testing triggers. The reports show clear numbers for opens, clicks, and delivery, which makes checking results easier.”

— Dixit’s review on G2

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Gmail — Beginners and Learning SMTP Integration

Probably the most established SMTP server on the market, Gmail isn’t designed for bulk emails, but it works for learning the ins and outs of SMTP. The 500 daily limit (2,000 for Workspace accounts) handles low-volume use cases without additional service signups.

Setup requires enabling “less secure apps” or generating app-specific passwords, adding friction compared to dedicated providers. For production applications, you’ll eventually need a proper SMTP service, not a Google SMTP, even if it works for prototyping.

One thing I enjoyed about Gmail’s SMTP is its simplicity for small-scale projects. However, setup requires enabling “less secure apps” or generating app-specific passwords, which introduces friction and security concerns. While it’s fine for prototyping, for production applications, a proper SMTP service is essential for reliability, scalability, and enhanced deliverability.

Key Features

• No additional signup required;
• Works with existing Google account;
• TLS encryption standard;
• Familiar interface for monitoring;
• Integrates with Google Workspace.

Limitations

• Daily sending cap. You can send a maximum of 500 emails per 24 hours with a free Gmail account, which can limit bulk or frequent sending;
• Recipient count. Sending one email to multiple recipients counts as multiple emails, reducing your overall daily quota (e.g., 100 recipients = 100 of your 500 emails);
• Deliverability risks. Since Gmail uses shared infrastructure, mass or bulk emails may get flagged as spam, affecting deliverability rates;
• Not suitable for large campaigns. Gmail isn’t designed for high-volume sending or email marketing, making it unreliable for large or regular campaigns;
• No marketing features. Gmail lacks automation, list segmentation, and advanced analytics that email marketing platforms offer.

Pros & Cons

Pricing

Google Workspace plans start at $6/month and increase the daily limit to 2,000. Gmail SMTP is free with any Google account but has a limitation of 500 emails per day. 

“Gmail is an excellent email service with a clean, user-friendly interface. If offers robust spam filters, ample storage and seamless integration with other Google services. Highly recommended for both personal and professional use!”

— Olivia’s review on Truspilot

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SendGrid — Enterprise-Level Scalability

SendGrid, now owned by Twilio, powers email for some of the internet’s largest senders. The free tier is modest—100 emails daily—but the platform scales infinitely when you need it. Enterprise features like dedicated IPs, subuser management, and advanced analytics are available as you grow.

The SMTP relay and API both perform excellently, with detailed documentation covering virtually every use case. SendGrid’s dedicated IP feature, coupled with IP warming, is a game-changer for high-volume senders. By gradually increasing email volume, you build a solid sender reputation, improving deliverability and reducing the risk of being flagged as spam.

All in all, if you’re building something that might scale significantly, you can’t go wrong starting with SendGrid.

Key Features

• SMTP and Web API options;
• Detailed event tracking;
• Email template engine;
• Subuser management for agencies;
• Expert deliverability services.

Limitations

• Low free‑plan sending cap. On the free plan you can only send about 100 emails per day;
• Free plan is being retired. As of recent updates, the free‑plan offering has been phased out, meaning that free plan is being turned into a 60-day trial;
• Very limited contact list & marketing‑features on free/basic tiers. On low-tier plans you get minimal contact‑storage and basic features only — advanced segmentation, automation, multi‑user support, or dedicated IPs are locked behind higher tiers;
• Shared IP deliverability risk for small users. Because free/basic users share IP pools, your deliverability may suffer (spam filters, blocklists), especially if other users abuse the shared IPs;
• Costs ramp up with volume. Once you exceed free or entry limits, scaling up (more emails, larger contact lists) quickly becomes more expensive compared with simpler SMTP‑focused providers.

Pros & Cons

Pricing

Paid plans start at $20/month for 100,000 emails. Free 60-day trial includes 100 emails per day forever. 

“SendGrid makes my life so much easier! I use it nearly daily in my capacity as a technical support specialist, and email issues are not uncommon. SendGrid not only makes the whole emailing setup and process seamless and easily integrates with all of our software, but also provides huge transparency and reporting into all of its functions.”  

— User’s review on G2

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Amazon SES — AWS Users and Cost-Effective Sending

Amazon’s Simple Email Service (SES) offers the lowest per-email costs in the industry—$0.10 per 1,000 emails after the free tier. If you’re already using AWS, SES integrates seamlessly with your existing infrastructure. If not—things are a bit trickier to get emails moving.

One thing that will put off many non-AWS users is the setup. Unlike dedicated email service providers that offer intuitive, user-friendly dashboards, SES requires a more technical setup through the AWS Management Console, which can be daunting for users not fluent in HTML. 

The platform lacks the polished, streamlined interfaces that make other providers like SendGrid or Brevo easier to navigate. But for developers who have experience with AWS—the cost savings are substantial.

Key Features

• Lowest per-email pricing available;
• AWS infrastructure integration;
• Dedicated IP options;
• SMTP configuration sets for tracking;
• Receiving email capability.

Limitations

• Free‑tier is small and temporary. The current free tier only grants up to 3,000 message charges/month for the first 12 months;
• Quota & rate limits apply. There’s a daily/24‑hour sending quota and a maximum send‑rate (emails per second). If you exceed these, SES will reject messages instead of queuing them;
• Sandbox restrictions until approval. By default (in “sandbox mode”), you may only send to/from verified email addresses/domains, and your sending limit may be very low;

Pros & Cons

Pricing

Prices start at $0.10 per 1,000 emails. Free tier includes 3,000 emails monthly when sending from EC2 (i.e., Amazon’s Cloud Infrastructure).

“​​The thing I appreciate most about Amazon SES is the ability to validate domains via DNS, which turns out to be a quick and intuitive process. The simple configurability and the generation of access credentials for sending emails make the service extremely practical. At FormaFarm, we use it with satisfaction for all our clients, ensuring reliability and efficiency.”

— Giuseppe’s review on G2 

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Conclusion: Top Picks for Free SMTP Servers

Choosing the right free SMTP service depends on your specific needs:

Best Overall SMTP Provider—Sender

Sender earns the top spot by combining a generous 15,000 monthly email allowance with an intuitive interface that doesn’t require a technical background. The platform balances transactional reliability with marketing features, making it versatile enough for most small business needs. Setup takes minutes, deliverability is solid, and the upgrade path won’t break your budget.

Best for High Volume Senders—SendPulse

SendPulse matches Sender’s 15,000 free emails while bundling multi-channel tools like SMS and push notifications. If you’re sending at scale and want room to grow across channels, SendPulse delivers volume without sacrificing features. The learning curve is steeper, but the capacity justifies the effort.

Best for Deliverability—SMTP2GO

SMTP2GO obsesses over inbox placement, offering detailed reporting that shows exactly where your emails land. Their reputation monitoring catches issues before they damage your sender score. The 1,000 monthly free emails are limited, but when deliverability matters more than volume, SMTP2GO is worth the trade-off.

Best for Developers—Mailtrap

Mailtrap’s email sandbox is something no developer should work without. Testing emails safely before production, inspecting spam scores, and debugging delivery issues—all without accidentally emailing real users. The production SMTP works well too, but the testing infrastructure alone makes Mailtrap essential for development workflows.

FAQs

What is an SMTP server?

An SMTP server is the infrastructure that sends emails across the internet. When your application or email client sends a message, it connects to an SMTP server that routes the email through various mail transfer agents until it reaches the recipient’s inbox. SMTP servers handle email authentication, encryption, and delivery—you provide the message, they handle the logistics.

Which SMTP port should I use?

Port 587 with TLS encryption is the modern standard for SMTP submission. Port 465 uses implicit SSL and works with some service providers. Port 25 is the traditional SMTP port but is often blocked by ISPs to prevent spam. When configuring your application, start with port 587—it offers the best compatibility and security.

What’s the difference between SMTP and API for sending emails?

SMTP uses the traditional email protocol—your application connects to a mail server and issues commands to send transactional messages. APIs use HTTP requests, sending email data directly to the provider’s servers. APIs typically offer better email performance, more detailed responses, and easier integration with modern applications. SMTP works universally but feels dated. Choose API when available; use SMTP for legacy systems or universal compatibility.

Do free SMTP servers have sending limits?

Yes, most SMTP servers have sending limits. Free tiers cap your sends daily, monthly, or both. Limits range from 100 emails per day (SendGrid) to 15,000 per month (Sender, SendPulse). Some also restrict subscribers, features, or require provider branding. Calculate your actual sending volume before choosing—exceeding limits means upgrading to paid plans or getting temporarily blocked.

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Disclaimer: This article evaluates the best free SMTP servers, including Sender, which our company owns. SMTP server comparisons and assessments are based on research, industry standards, and user feedback. No commissions are earned from links in this article.