Email not arriving: find the cause
Three cases look alike but have different causes: the email is rejected, it lands in spam, or it disappears. Knowing which one applies saves most of the time.
1. The email is rejected
The sender gets an error message (bounce) with a code such as 550 or 554. The text usually names the reason: unknown address, blocklist, missing authentication or a policy.
- The message names a blocklist: blacklist check and removal guides.
- The message names SPF, DKIM or DMARC: domain check.
- The message names an encrypted connection: SMTP test.
2. The email lands in spam
The email arrives, but in the spam folder. Common causes are missing or faulty authentication, poor reputation of the sending domain, and content. The email test checks all of this on a real email and shows each cause.
3. The email disappears
The sender sees no bounce, the recipient gets nothing. This often happens with greylisting (the server asks for a second delivery after a few minutes), with filters that discard mail silently, or with a blocklist that is not queried. First check whether the email is in spam or promotions.
What to do
- Read the error message or the header of the email (header analyzer).
- Check the domain with the domain check. It shows SPF, DKIM, DMARC, encryption and blocklists.
- Fix the finding using the instructions in the result.
- Test again with a real email in the email test.
Terms that come up are explained in the glossary.