Free SMTP Relay: Best Options for Sending Transactional Emails
Find the best free SMTP relay services for transactional emails. Compare sending limits, features, and setup guides for Brevo, Gmail, SendGrid, and more.
You need to send password resets, order confirmations, and account notifications from your application. You know that sending from your own server’s mail function leads to poor deliverability. But you’re not ready to commit to a paid SMTP service yet.
Free SMTP relay services bridge this gap. They route your outgoing emails through dedicated infrastructure with established sender reputations, giving you significantly better deliverability than a self-hosted solution — at no cost.
This guide compares the best free SMTP relay options, explains what you can realistically accomplish with each, and walks through setup considerations.
What Is SMTP Relay?
SMTP relay is the process of routing outgoing email through an intermediate server rather than sending directly from your own infrastructure. Instead of your application’s server connecting directly to the recipient’s mail server, it hands the email to a relay server that handles delivery on your behalf.
Why SMTP Relay Matters
| Direct Sending | SMTP Relay |
|---|---|
| Your IP has no established reputation | Relay IP has established reputation |
| No bounce handling | Automatic bounce processing |
| No delivery tracking | Opens, clicks, bounce tracking |
| Manual SPF/DKIM setup | Guided authentication setup |
| Risk of IP blacklisting | Managed IP reputation |
| Limited throughput | High-volume capable |
The primary advantage of SMTP relay is deliverability. ISPs evaluate sender reputation when deciding whether to deliver email to the inbox. A relay service with years of established reputation gives your emails a significant advantage over sending from your own unproven IP address.
Best Free SMTP Relay Services
1. Brevo
Best for: Most businesses starting with transactional email
Brevo’s free plan includes SMTP relay with 300 emails per day — no time limit, no credit card required. This is sufficient for small applications, development environments, and businesses sending under 9,000 transactional emails per month.
| Feature | Free Plan Details |
|---|---|
| Daily limit | 300 emails/day |
| Monthly limit | ~9,000 emails/month |
| Time restriction | None (permanent free tier) |
| API access | Yes (REST API + SMTP) |
| Tracking | Opens, clicks, bounces, delivery |
| Authentication | SPF, DKIM support |
| Additional features | Contact management, email templates |
Setup complexity: Low. Create an account, verify your domain, and configure SMTP credentials in your application.
When to upgrade: When you consistently need more than 300 emails/day. Paid plans start at $9/month for 5,000 emails/month.
Brevo’s free SMTP relay works seamlessly with Tajo for e-commerce transactional emails. Tajo automatically routes order confirmations, shipping notifications, and account emails through Brevo’s relay, ensuring reliable delivery while keeping customer interaction data synchronized.
2. Gmail SMTP
Best for: Very low-volume sending or development/testing
Gmail allows you to use its SMTP servers to send email from your application. Personal Gmail accounts allow 500 emails/day; Google Workspace accounts allow 2,000/day.
| Feature | Free Plan Details |
|---|---|
| Daily limit | 500/day (personal) or 2,000/day (Workspace) |
| Monthly limit | ~15,000/month (personal) |
| Time restriction | None |
| API access | SMTP only (or Gmail API) |
| Tracking | None built-in |
| Authentication | Google’s SPF/DKIM |
| Additional features | None for relay use |
Setup complexity: Medium. Requires enabling “Less secure apps” or creating an App Password with 2FA enabled. Google may block access without warning.
Limitations: No delivery tracking, no bounce handling, no webhook notifications. Google may temporarily block your account if sending patterns look unusual. Not suitable for production transactional email.
3. Amazon SES
Best for: Developers with AWS infrastructure needing high-volume free sending
Amazon SES offers 62,000 free emails per month — but only when sent from an EC2 instance. Outside of EC2, there’s no free tier.
| Feature | Free Plan Details |
|---|---|
| Daily limit | No daily limit |
| Monthly limit | 62,000 emails/month (from EC2) |
| Time restriction | None (permanent free tier from EC2) |
| API access | REST API + SMTP |
| Tracking | Opens, clicks, bounces via SNS |
| Authentication | SPF, DKIM, DMARC support |
| Additional features | Email receiving, templates |
Setup complexity: High. Requires AWS account, EC2 instance, SES configuration, IAM permissions, and production access request (starts in sandbox mode). You must build your own dashboard and monitoring.
When to upgrade: You pay $0.10 per 1,000 emails beyond the free tier, or when sending from outside EC2.
4. SendGrid
Best for: Developers wanting a dedicated email API with a free tier
SendGrid’s free plan allows 100 emails/day permanently. While the daily limit is lower than Brevo or Gmail, SendGrid offers robust developer tools and documentation.
| Feature | Free Plan Details |
|---|---|
| Daily limit | 100 emails/day |
| Monthly limit | ~3,000 emails/month |
| Time restriction | None (permanent free tier) |
| API access | REST API + SMTP + Web API v3 |
| Tracking | Opens, clicks, bounces |
| Authentication | SPF, DKIM support |
| Additional features | Template editor, event webhooks |
Setup complexity: Low to medium. Well-documented setup process with comprehensive developer guides.
5. Mailgun
Best for: Developers needing email validation alongside SMTP relay
Mailgun offers a free trial with 100 emails/day for the first three months, after which you need a paid plan. The platform includes email validation and inbound routing capabilities.
| Feature | Free Plan Details |
|---|---|
| Daily limit | 100 emails/day |
| Monthly limit | ~3,000 emails/month |
| Time restriction | 3-month trial, then paid |
| API access | REST API + SMTP |
| Tracking | Opens, clicks, bounces |
| Authentication | SPF, DKIM support |
| Additional features | Email validation, inbound routing |
Setup complexity: Medium. Requires domain verification and DNS configuration.
6. Elastic Email
Best for: Businesses wanting affordable scaling beyond free limits
Elastic Email provides 100 free emails/day with very competitive paid pricing when you need to scale.
| Feature | Free Plan Details |
|---|---|
| Daily limit | 100 emails/day |
| Monthly limit | ~3,000 emails/month |
| Time restriction | None (permanent free tier) |
| API access | REST API + SMTP |
| Tracking | Opens, clicks, bounces |
| Authentication | SPF, DKIM support |
| Additional features | Template builder, contact management |
Free SMTP Relay Comparison
| Provider | Daily Limit | Monthly Limit | Tracking | Setup Ease | Time Limit |
|---|---|---|---|---|---|
| Brevo | 300 | ~9,000 | Full | Easy | None |
| Gmail | 500-2,000 | ~15,000 | None | Medium | None |
| Amazon SES | No limit | 62,000* | Via SNS | Hard | None |
| SendGrid | 100 | ~3,000 | Full | Easy | None |
| Mailgun | 100 | ~3,000 | Full | Medium | 3 months |
| Elastic Email | 100 | ~3,000 | Full | Easy | None |
*Amazon SES free tier requires sending from EC2 instances.
Setting Up a Free SMTP Relay
Prerequisites
Before configuring any SMTP relay, you need:
- A verified domain — You should send from an address at your own domain (e.g., [email protected]), not from a free email address
- DNS access — You’ll need to add SPF and DKIM records to your domain’s DNS
- Application access — The ability to configure SMTP settings in your application, CMS, or framework
General Setup Process
Step 1: Create your account with the chosen provider and verify your email address.
Step 2: Add your sending domain. Enter your domain name and follow the provider’s verification process.
Step 3: Configure DNS records. Add the SPF and DKIM records provided by your SMTP relay service. These authenticate your emails and are essential for deliverability. For detailed instructions, see our SPF, DKIM, and DMARC guide.
Step 4: Get SMTP credentials. Your provider will give you:
- SMTP server address (e.g., smtp-relay.brevo.com)
- Port (typically 587 for TLS or 465 for SSL)
- Username (usually your email or a generated key)
- Password (generated API key or account password)
Step 5: Configure your application. Enter these credentials into your application’s email settings. Most frameworks, CMS platforms, and applications have SMTP configuration options.
Step 6: Send a test email to verify everything works. Check that the email arrives in the inbox (not spam) and that tracking is functional.
Common Configuration Examples
Most web applications support SMTP configuration. Here are the settings you’ll typically need:
| Setting | Value |
|---|---|
| SMTP Host | Provider-specific (e.g., smtp-relay.brevo.com) |
| Port | 587 (TLS) or 465 (SSL) |
| Encryption | TLS (recommended) or SSL |
| Authentication | Yes (required) |
| Username | Account email or API key |
| Password | API key or generated password |
Free SMTP Relay Best Practices
Separate Transactional and Marketing Email
Use your free SMTP relay exclusively for transactional emails (order confirmations, password resets, notifications). Marketing emails have different sending patterns and engagement rates that can negatively affect the reputation of your transactional sending.
Most providers recommend — and some require — separate sending streams for transactional and marketing email. This ensures that a marketing campaign with high unsubscribe rates doesn’t damage the deliverability of your critical transactional messages.
Monitor Your Sending Reputation
Even with a free plan, monitor these metrics:
- Bounce rate: Keep under 2%. Higher rates indicate list quality issues.
- Spam complaint rate: Keep under 0.1%. Higher rates damage your reputation.
- Delivery rate: Should be above 95%. Lower rates suggest authentication or content issues.
Handle Bounces Properly
When an email bounces, stop sending to that address immediately. Most SMTP relay services handle this automatically through suppression lists, but verify that your application respects these signals and doesn’t re-add bounced addresses to your sending queue.
Rate Limit Your Sending
If your application generates bursts of emails (e.g., during a batch process), implement rate limiting to stay within your free tier limits and avoid triggering spam filters with sudden volume spikes.
When to Upgrade from Free SMTP Relay
Free SMTP relay services are excellent for getting started, but certain signals indicate it’s time for a paid plan:
- You’re hitting daily limits regularly and delaying critical transactional emails
- You need dedicated IP for better deliverability control
- Volume exceeds free limits and you’re queuing or dropping messages
- You need priority support for delivery issues
- Your business depends on email and you can’t afford downtime
For most growing businesses, the transition point comes around 10,000-15,000 emails per month. At this volume, a paid plan from Brevo (starting at $9/month) or a similar provider costs less than the business impact of unreliable delivery.
Free SMTP Relay for E-Commerce
E-commerce businesses have specific transactional email needs that make free SMTP relay particularly valuable during early growth stages:
- Order confirmations: Customers expect immediate confirmation after purchase
- Shipping updates: Tracking notifications reduce support inquiries
- Password resets: Must be delivered within seconds for security
- Account verification: Double opt-in and email verification flows
- Abandoned cart reminders: Time-sensitive recovery emails
With Tajo’s Brevo integration, these transactional emails are automatically triggered by store events and sent through Brevo’s SMTP relay. The free 300 emails/day limit supports e-commerce stores processing up to 50-75 orders per day (accounting for multiple transactional emails per order), making it an effective solution for growing stores.
Conclusion
Free SMTP relay services provide a practical path to reliable email delivery without upfront costs. For most businesses starting out, Brevo’s free plan offers the best combination of daily volume (300 emails/day), built-in tracking, and growth path to paid plans. For developers with AWS infrastructure, Amazon SES’s 62,000 free monthly emails is hard to beat on volume alone.
Choose based on your volume needs, technical resources, and growth trajectory. Start with the free tier, validate your setup with test emails, and upgrade when your sending volume demands it. For more on SMTP configuration and email infrastructure, see our complete SMTP guide.