Supabase Auth email that survives real signups.

Supabase's built-in email service is rate-limited and meant for testing — real signups outrun it fast. Point Supabase Auth's custom SMTP at the NoticeAPI relay on port 465, and every confirmation, magic link, and reset leaves a domain you verify, into the same logs, suppressions, and signed webhooks as your API sends.

Get an API key Read the SMTP docs
Shortest working path
Supabase Auth SMTP settings
Host: smtp.noticeapi.com
Port: 465
Secure: true
Username: noticeapi
Password: ntc_xxxxxxxxxxxxxxxxxxxx
Sender email: [email protected]
Sender name: Acme

Connect it, test it, then move traffic.

  1. 1

    Verify your sending domain

    Add the domain your auth email should come from and publish its SPF and DKIM records.

  2. 2

    Create an API key

    Generate a key with the ntc_ prefix. It becomes the SMTP password.

  3. 3

    Enter it in Supabase

    Turn on custom SMTP in Supabase Auth and set the host, port 465, TLS, sender, and your key.

  4. 4

    Send a test signup

    Trigger a confirmation, reset, or magic link, then watch it land in the NoticeAPI log.

What remains visible after integration.

Drop-in for Supabase's SMTP fields

Paste the relay host, port 465, and your ntc_ key into Supabase's custom SMTP settings. No auth code changes.

Sends from your verified domain

Confirmation and reset mail leave a domain you verify with SPF and DKIM, not a default shared sender.

Every auth send in the log

Confirmation, magic link, and reset land in the same logs and recipient timelines as your API sends, so you can prove one arrived.

Route outcomes to your stack

Signed webhooks push delivery, bounce, and complaint events into your own systems as they happen.

Keep the auth path transactional

This relay carries confirmation, login, and account-recovery mail. Product updates and campaigns belong in NoticeAPI audiences, with tracked subscriptions and one-click unsubscribe.

Read the implementation.

SMTP docsHost, port 465, implicit TLS, and API-key auth.Domain docsPublish SPF and DKIM before production auth email.Magic link emailsDeliver passwordless login links and watch them land.Simulator testingDry-run auth email against the simulator first.

Questions before you ship.

Does NoticeAPI manage Supabase users?

No. Supabase owns auth and user state; NoticeAPI relays the mail and records where it landed.

Which SMTP port should I use?

Use port 465 with implicit TLS and your NoticeAPI API key as the password.

Can I run marketing through the same account?

Yes. Send campaigns through NoticeAPI audiences with one-click unsubscribe, not the Supabase Auth SMTP path.

Test it. Then send for real.

Simulator outcomes are free. Move to a verified domain when the path is ready.

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