Supabase SMTP

Send Supabase Auth emails — confirmations, magic links, password resets — through eusend by configuring custom SMTP in your Supabase project.

Supabase's built-in email service is rate-limited and meant only for testing — in production you must bring your own SMTP provider for auth emails (confirmations, magic links, password resets, invites). Pointing Supabase at eusend gives you DKIM-signed delivery on your own domain, with every auth email visible in your eusend dashboard.

Connection values

Parameter	Type	Description
`Host`required	`smtp.eusend.dev`	The submission server.
`Port`required	`465`	Implicit TLS. Use 2465 if 465 is blocked.
`Username`required	`eusend`	The literal string "eusend".
`Password`required	`eu_live_…`	Any eusend API key.
`Sender email`required	`[email protected]`	Must be a verified domain.

Setup

Open SMTP settings

In the Supabase dashboard go to Authentication → Emails → SMTP Settings and toggle on Enable Custom SMTP.

Enter the connection

Supabase → Custom SMTP

Host:          smtp.eusend.dev
Port:          465
Username:      eusend
Password:      <an eusend API key, eu_live_…>
Sender email:  [email protected]   (must be a verified domain)
Sender name:   Your App

Save.

Send a test email

Use Supabase's Send test email button — it exercises the whole path end to end. A delivered test confirms your key and sender domain are correct.

ℹ

The sender email must be an address on a domain you have verified in eusend. A 550 back means the sender domain isn't verified; a 535 means the username or key is wrong.

Adjust the rate limit

Supabase caps auth email throughput separately from your SMTP provider. Under Authentication → Rate Limits, raise "Rate limit for sending emails" to match your expected sign-up volume — otherwise Supabase, not eusend, becomes the bottleneck. eusend's own sending limits still apply on top.

Note on password recovery links

Auth emails are generated and sent by Supabase itself; eusend is only the transport. Customize the templates under Authentication → Emails → Templates in Supabase. Everything eusend adds — DKIM, tracking, suppression — is applied to whatever Supabase hands off.