You got **Email used fallback domain** or **Workflow email used fallback domain**. The recipient got mail, but **not** from the From domain you configured. Lumail retried through a fallback you set on **Domains**.

The display name and local part stay the same; only the domain changes (`Melvyn <hello@primary.com>` → `Melvyn <hello@fallback.com>`).

## What to change

1. Open **Domains**. The alert names the primary host and the fallback that was used.
2. Fix the **primary** domain — usually MAIL FROM, SES identity, or DKIM. Use the error sentence in the notification:
   - [How to fix MAIL FROM](/docs/deliverability/how-to-fix-mail-from)
   - [How to verify a sending domain](/docs/deliverability/how-to-verify-sending-domain)
   - [How to fix DKIM](/docs/deliverability/how-to-fix-dkim)
3. Verify the primary domain. New sends stop using the cached fallback (Lumail caches a successful fallback for 10 minutes for that org + primary).
4. If no fallback is configured and you want this safety net, set **Fallback** priority on a second verified domain.

Fallback does **not** fix account-level pause, quota, or a missing configuration set.

## Related

- [Email Domains](/docs/domains/email-domains) — fallback priorities
- [How to fix a failed send](/docs/deliverability/how-to-fix-email-send-failure)