9 Best Free SMTP Relay Services

I spent an entire afternoon on a problem that turned out to be one setting.

A client's WordPress site had a contact form. People filled it in, hit send, and nothing arrived. No error, no bounce, no email. Just silence. We checked the form plugin, the theme, the database. All fine.

The actual problem was that the website was trying to send mail by itself, straight from the hosting server. No reputation, no authentication, no chance. Gmail was quietly binning every message.

The fix took ten minutes. We pointed the site at a free SMTP relay, and the emails started arriving instantly.

So I went and tested the main free SMTP relay services properly. I checked the free limits, the setup, where the emails landed, and the small print. Here is everything I found.

What Is an SMTP Relay

Let me keep this plain.

SMTP relay is when your app, website, or device hands its email to a separate mail server, and that server delivers it for you.

That is it.

You are not sending the email yourself anymore. You are passing it to a service with the trucks, the routes, and the reputation to get it delivered. Your WordPress site, your app, or your office scanner just says "here, take this," and the relay handles the rest.

Think of it like posting a parcel. You could drive it across the country yourself, and maybe it arrives. Or you hand it to a courier who does this all day, has the network, and gets it there. The relay is the courier.

A free SMTP relay does this at no cost, up to a monthly or daily limit.

SMTP Relay vs SMTP Server: What Is the Difference

People use these terms interchangeably, and mostly that is fine, but here is the honest distinction.

An SMTP server is any machine that handles sending email. Your own mail server is an SMTP server.

An SMTP relay is the specific job of forwarding mail through someone else's server on your behalf. It is a service you point your system at.

In practice, when people say "free SMTP relay" they mean a hosted service you plug your app or website into so it stops trying to send mail on its own. That is what this guide covers. If you want the broader roundup of sending platforms, see our guide to the best free SMTP servers.

When You Need an SMTP Relay

You need one more often than you would think. Here are the common cases.

A website contact form. The classic. WordPress and similar systems send mail through the hosting server by default, which is exactly why so many contact forms silently fail.

An app sending user emails. Sign up confirmations, password resets, receipts, notifications. Anything triggered by a user action.

Office devices. Scanners, printers, and security systems that email you documents or alerts. These almost always need a relay with a username and password.

Internal tools and scripts. Backup reports, monitoring alerts, cron jobs that email you when something breaks.

A newsletter or campaign. When you outgrow sending by hand and want proper delivery and tracking.

The pattern is the same in all of them. Something needs to send email, and it has no reputation of its own.

Quick Comparison Table

Free limits and prices change often, so always check each provider's own pricing page before you commit.

What to Look For in a Free SMTP Relay

After setting up my share of these, here are the six things that matter.

Deliverability. The whole reason you are using a relay. Look for a provider with a clean sending reputation and support for SPF, DKIM, and DMARC.

The real free limit. Read carefully. A daily cap and a monthly pool behave very differently. A daily cap can block you on a busy day even if your monthly total is small.

Easy setup. You want clear credentials, a host, a port, and simple docs. Some relays take five minutes. Others need a developer.

Authentication support. Your relay should let you authenticate your own domain so mail goes out as you, not as a generic sender. This matters enormously for inbox placement.

Logs and analytics. When something does not arrive, you need to see why. Delivery logs save hours of guessing.

Room to grow. When you outgrow the free tier, the paid step up should be fair, not a cliff.

The 9 Best Free SMTP Relay Services

1. TrueEmailer: Best Overall

Best for: anyone who wants relaying plus a real fight for the inbox.

I am putting TrueEmailer first, and yes, this is our blog. But it fits this problem well, because a relay only helps if the mail actually lands, and that is the whole design.

Most free relays hand off your email and leave your reputation entirely to you. TrueEmailer does more. Its deliverability layer sets up SPF, DKIM, and DMARC for you and runs a spam shield before sending, and its automatic warmup agent builds your sender reputation in the background. That last part matters most when your domain is new and has no track record, which is exactly when relays disappoint people.

You also get an analytics agent you can chat with to check delivery, plus a full campaign side with an AI writer and interactive AMP emails when you are ready to send more than transactional mail.

Who should use it and why: businesses that want one service for both their app's transactional email and their marketing, without babysitting deliverability. If your mail keeps landing in spam despite using a relay, this is built for that.

Try it for free. Check current pricing here.

2. Brevo

Best for: websites and small businesses that want a generous daily allowance.

Brevo offers a straightforward SMTP relay alongside its marketing tools, with 300 emails a day free. It has a strong sending reputation and simple credentials you can drop into WordPress in a couple of minutes.

Who should use it and why: small business websites and contact forms. If you want one account for both your site's mail and your newsletter, this is an easy pick.

3. Mailjet

Best for: the biggest free monthly pool.

Mailjet gives you 6,000 emails a month free, with no card needed. It supports several SMTP ports, which helps when a network blocks the usual ones, and it handles both transactional and marketing mail.

Who should use it and why: anyone whose sending is bursty rather than steady, since a monthly pool is more forgiving than a daily cap.

4. MailerSend

Best for: startups that want a clean, modern relay.

MailerSend offers 3,000 emails a month free with SMTP, API, good logs, and suppression management. Setup is quick and the dashboard is pleasant.

Who should use it and why: startups and small product teams who want something modern that both developers and non developers can navigate.

5. SendGrid

Best for: projects that will grow into serious volume.

SendGrid is a battle tested relay with 100 emails a day free forever. It scales smoothly, has strong uptime, and offers deep reporting once you dig in.

Who should use it and why: teams who know volume is coming and want to set up once on infrastructure that will not need replacing.

6. Mailgun

Best for: developers who want control.

Mailgun provides an SMTP relay plus a strong API, webhooks, and detailed logs. The free tier is more of a trial now, so check current terms, but the platform is mature.

Who should use it and why: technical teams building email into a product who want fine control over routing and tracking.

7. Amazon SES

Best for: huge volume on a tight budget.

Amazon SES offers SMTP relay at roughly ten cents per thousand emails, with 3,000 free a month in your first year and more if you send from an app on EC2.

Who should use it and why: technical teams sending at real scale who have engineers to handle the setup and the sandbox process. Not for beginners.

8. SMTP2GO

Best for: simple, reliable relaying.

SMTP2GO has been doing this since 2006 and it shows. Setup is genuinely easy, deliverability is strong, and you get 1,000 emails a month free.

Who should use it and why: non technical users who want a relay that just works, especially for office devices and internal systems.

9. Gmail SMTP

Best for: testing and tiny personal projects.

Gmail can act as a relay for small sends, and it is free with any account. But you cannot control DNS or authentication, and the daily limits are strict.

Who should use it and why: students, hobbyists, and anyone testing a setup. Do not use it for anything that matters or anything at volume.

How to Set Up a Free SMTP Relay

The process is the same almost everywhere. Here it is in six steps.

Step 1: Create an account with your chosen relay and verify your email.

Step 2: Add and verify your domain. The provider gives you DNS records for SPF and DKIM. Add them in your domain provider's DNS settings. This is the step people skip, and it is the most important one for landing in the inbox.

Step 3: Get your credentials. The provider gives you a host, a port, a username, and a password or API key. Copy them somewhere safe.

Step 4: Pick your port. Use 587 with TLS in most cases, since it is the modern standard. Use 465 if your system requires implicit SSL. Avoid port 25, which is blocked on most networks and associated with spam.

Step 5: Enter the details into whatever is sending. In WordPress that means an SMTP plugin. In an app it goes in your mail configuration. On a device it goes in the email settings.

Step 6: Send a test. Then check it arrived, and check the provider's logs to confirm it went out cleanly. If it landed in spam, your DNS records are usually the culprit.

Common SMTP Relay Problems and Fixes

Emails go to spam. Almost always missing or wrong authentication. Verify your SPF and DKIM records are correct and that you are sending from your verified domain, not a generic address.

Connection refused or timing out. Usually a blocked port. Try 587 instead of 25. Some hosts and office networks block outgoing mail ports entirely.

Authentication failed. Check your username and password. Many providers use an API key as the password rather than your account password, which catches people out.

Emails send but never arrive. Check the provider's delivery logs first. They will tell you whether it was delivered, bounced, or blocked, which saves hours of guessing.

Hitting the free limit early. Watch daily versus monthly caps. If you keep hitting a daily cap on busy days, move to a provider with a monthly pool.

Everything works, then stops. Often a reputation problem from sending too much too fast on a new domain. This is what warmup exists to prevent.

Frequently Asked Questions

What is a free SMTP relay?

It is a service that sends email on behalf of your app, website, or device, at no cost up to a set limit. Instead of your system trying to deliver mail itself, it hands the message to a provider with an established sending reputation.

What is the best free SMTP relay in 2026?

There is no single winner. For relaying plus built in warmup and deliverability, TrueEmailer is a strong pick. For the biggest free monthly pool, Mailjet gives 6,000. For a generous daily allowance, Brevo gives 300 a day.

Is SMTP relay free?

Yes, up to a limit. Brevo, Mailjet, MailerSend, SendGrid, SMTP2GO, and TrueEmailer all offer free tiers. They cap how many emails you can send per day or month, which is plenty for a contact form or a small app.

Which SMTP port should I use for relaying?

Use port 587 with TLS in most cases, since it is the modern standard for authenticated sending. Use 465 if your system requires implicit SSL. Avoid port 25, which is widely blocked and associated with spam.

Why are my relayed emails still going to spam?

Usually because your domain is not properly authenticated. Make sure SPF, DKIM, and DMARC records are set up correctly and that you are sending from your verified domain. A new domain also needs warmup before it earns trust.

Can I use Gmail as an SMTP relay?

For testing or very small personal projects, yes. But Gmail has strict daily limits and gives you no control over authentication for your own domain, so it is not suitable for business use, apps at scale, or marketing.

Do I need a relay for a WordPress contact form?

Almost certainly yes. WordPress sends mail through your hosting server by default, which typically has no sending reputation and no authentication. That is the single most common reason contact form emails vanish.

Final Word

That wasted afternoon taught me something I now check first every time. If email is not arriving, do not start with the form or the code. Start with how it is being sent.

A free SMTP relay solves it, and it costs nothing to start. Point your site or app at a proper sending service, verify your domain, and your email starts landing where it should.

If you want a relay that also warms up your domain and fights to keep your mail out of spam, start free with TrueEmailer today.

Your contact form, and your sender reputation, will thank you.