Send emails with SMTP
Learn how to integrate Resend via SMTP.
Prerequisites
To get the most out of this guide, you’ll need to:
Prefer watching a video? Check out our video walkthrough below.
SMTP Credentials
When configuring your SMTP integration, you’ll need to use the following credentials:
- Host:
smtp.resend.com - Port:
25,465,587,2465, or2587 - Username:
resend - Password:
YOUR_API_KEY
Ports help to instruct the type of security you want to use in your SMTP connection.
| Type | Port | Security |
|---|---|---|
| SMTPS | 465, 2465 | Implicit SSL/TLS (Immediately connects via SSL/TLS) |
| STARTTLS | 25, 587, 2587 | Explicit SSL/TLS (First connects via plaintext, then upgrades to SSL/TLS) |
Custom Headers
If your SMTP client supports it, you can add custom headers to your emails.
Here are some common use cases for custom headers:
- Prevent threading on Gmail with the
X-Entity-Ref-IDheader - Include a shortcut for users to unsubscribe with the
List-Unsubscribeheader
FAQ
Once configured, you should be able to start sending emails via SMTP. Below are some frequently asked questions:
What if I need logs from the server to debug?
What if I need logs from the server to debug?
We currently don’t provide SMTP server logs for debugging. If you run into issues, please reach out to support.
Where do I see the emails sent with SMTP?
Where do I see the emails sent with SMTP?
Emails sent with SMTP will show in your emails table.
Does the rate limit apply when sending with SMTP?
Does the rate limit apply when sending with SMTP?
Yes, the rate limit is the same as the API.