You got **Campaign email has invalid HTML** or **Campaign email failed to render**. Lumail never handed the message to the email system. No recipients were sent for that attempt.

## What to change

1. Open the campaign from the notification.
2. **Invalid HTML** — a block or raw HTML snippet doesn’t parse. In the editor, remove recently pasted HTML, custom code blocks, or broken tags. Re-save and send a test to yourself.
3. **Failed to render** — usually a bad variable, snippet, or image/source the renderer can’t load. Check:
   - mustache variables with unmatched braces
   - snippets that were archived
   - image URLs that 404 or aren’t `https`
4. Send a test. When the test renders, send or resume the campaign.

DNS will not fix a render error.

## Related

- [Variables](/docs/features/variables)
- [Content Deliverability Checker](/docs/features/content-deliverability)
- [How to fix a failed campaign](/docs/deliverability/how-to-fix-failed-campaign)