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Clerk +clerk_test email not received: since October 26, 2026, Clerk sends no email to test addresses while Test mode is on

By Ohad Krispin, founder of VibeRaven · LinkedIn

Since October 26, 2026, Clerk sends no email to a test email address, one with the +clerk_test subaddress such as jane+clerk_test@example.com, while Test mode is on in the Clerk Dashboard. Before that, it skipped only verification codes and new device sign-in notices and still delivered sign-in links, invitations and receipts, so a test that opens an inbox to follow a sign-in link or accept an invitation now waits for an email that never comes. Tests that sign in with the fixed verification code 424242 need no change. For a flow that has to read an email, send it to an address without +clerk_test, which Clerk delivers and counts toward the development instance email limit, or check the email.created webhook, which still fires with delivered_by_clerk set to false. Checked against Clerk's changelog and testing docs on 2026-10-28.

Same symptom with Supabase Auth? See why Supabase confirmation emails do not arrive.

What changed on October 26

Clerk's changelog says most test addresses are not real inboxes, so the emails it used to deliver to them bounced, and those bounces hurt email delivery for every development instance. Now no email goes to a +clerk_test address while Test mode is on: no verification codes, verification links, invitations or security notifications. The emails are still recorded.

Clerk's testing docs say to complete verification for a test email address with the code 424242. Clerk does not send verification links to test addresses, so turn on the Email verification code setting and test that flow instead of a link. Fictional phone numbers from +1 (XXX) 555-0100 to +1 (XXX) 555-0199 work the same way: no SMS is sent, and 424242 verifies them.

Tests that have to read the email

A test that follows a sign-in link or accepts an invitation needs an address without +clerk_test, at an inbox the test can read. Those emails are delivered as before and count toward the development instance limit, which Clerk's testing docs put at 100 emails and 20 SMS messages per calendar month. A test that only needs to know an email was sent can listen for the email.created webhook, where delivered_by_clerk is false for an email Clerk skipped.

Checklist

Fix tests that waited for a Clerk email

  1. 01
    Find the tests that use test addresses:
    grep -rn "+clerk_test" --exclude-dir=node_modules .
  2. 02Switch each test that signs in by link to the email code flow with 424242, after turning on Email verification code in the Clerk Dashboard.
  3. 03Send the emails a test must open, such as invitations, to a real test inbox without +clerk_test.
  4. 04Where a test only checks that an email was sent, assert on the email.created webhook and its delivered_by_clerk field.

Related

Sources

Official docs behind this checklist

Browse all launch guides · Read resources · How to make and check your next change

FAQ

FAQ for builders before launch

Does the 424242 code still work?

Yes. Clerk says tests that sign in with 424242 need no change.

Is a real user with +clerk_test in their address affected?

Only while Test mode is on. Clerk's testing docs say every development instance has Test mode on by default, and that turning it on for a production instance is possible but highly discouraged; the switch is on the instance's Settings page in the Clerk Dashboard.