You got a send failure such as **Message rejected**, **Email delivery failed**, **Workflow email send failed**, or **campaign send failed**. The message never left, or the provider refused it.

## What to change

1. Open the linked campaign, workflow, or **Domains** page from the notification.
2. Read the last sentence of the alert — it names the provider code.
3. Fix the matching cause:

| Code / wording | Fix |
| --- | --- |
| MAIL FROM / `MailFromDomainNotVerifiedException` | [How to fix MAIL FROM](/docs/deliverability/how-to-fix-mail-from) |
| Domain not verified / identity paused | [How to verify a sending domain](/docs/deliverability/how-to-verify-sending-domain) |
| Invalid from/to/subject/headers | [How to fix an invalid email parameter](/docs/deliverability/how-to-fix-invalid-email) |
| Configuration set missing / sending paused | [How to fix sending infrastructure](/docs/deliverability/how-to-fix-sending-infrastructure) |
| Rate or daily quota | [How to fix sending rate or daily quota](/docs/deliverability/how-to-fix-sending-rate) |
| Internal error / “bug on our side” | Nothing on your DNS. Email [support@lumail.io](mailto:support@lumail.io) with the org slug and the technical detail. |
| Message rejected (generic) | Confirm the From address uses a **verified** custom domain, the recipient is not suppressed, and the campaign still renders. Then retry. |

4. After DNS changes, verify the domain, then resend or resume the campaign/workflow.

Fallback already delivered through another domain? See [How to fix a fallback-domain send](/docs/deliverability/how-to-fix-fallback-domain).

## Related

- [Email Domains](/docs/domains/email-domains)
- [How to fix a failed campaign](/docs/deliverability/how-to-fix-failed-campaign)