Custom SMTP sender does not persist in Auth Email settings (Brevo)

[rsnadvisors]

Hi Supabase team,

I am troubleshooting Auth email delivery for project piura-responde-dev (project ref ebeuxsjnlbtieggxhbhm).

Current setup:

• Auth email confirmations are enabled.
• Custom SMTP is enabled.
• SMTP provider is Brevo.
• SMTP host: smtp-relay.brevo.com
• Port: 587
• Domain perudecide.com is authenticated in Brevo.
• Sender noreply@perudecide.com is verified in Brevo.

Problem:

• In Authentication -> Emails -> SMTP Settings, I change Sender email address from empresasdelnorte@gmail.com to noreply@perudecide.com.
• The UI accepts the change temporarily, but after reload it reverts to empresasdelnorte@gmail.com.
• I also observed 400/500 events in the embedded activity/log area during or after save attempts.

What I already checked:

• Brevo sender is active/verified.
• Domain DNS was configured and validated.
• SMTP username/password were re-entered.
• Fresh SMTP credentials were tested.
• Clean browser session/tab was tested.
• Toggling Custom SMTP off/on did not persist reliably after reload.

Because the sender value is not persisting, I cannot complete a clean verification email test with the intended sender.

Does this look like a known Studio/backend persistence bug for Auth SMTP settings, or is there any hidden validation requirement for the sender field?

I also opened a support ticket for the same issue: SU-424697.

Thanks!

[Nikolai-Lazovatskii]

Hi, had the same thing happen with a different provider, its almost certainly not the sender field itself.
That form never echoes your SMTP password back after a reload, so the field is empty. When you edit just the sender and save, the whole auth config gets submitted with an empty smtp_pass, the api rejects it with 400, and everything silently reverts. Thats why toggling custom SMTP off and on didn't stick either.
Try changing the sender and re-entering the SMTP password in the same save. You can confirm the theory in devtools in Network: look at the failing patch to /config/auth, the response body has the actual validation error, Studio just doesnt show it.

If it still won't stick, bypass Studio and set it through the Management api:

curl -X PATCH "https://api.supabase.com/v1/projects/<project-ref>/config/auth" \
  -H "Authorization: Bearer <personal-access-token>" \
  -H "Content-Type: application/json" \
  -d '{"smtp_admin_email":"noreply@perudecide.com","smtp_pass":"<brevo smtp key>"}'

then GET the same endpoint to check it actually saved. Whatever the GET returns is what GoTrue really uses, regardless of what Studio displays. And if the API call itself comes back 400/500 - paste that response body into your support ticket it'll get routed much faster