Nearly every report of a missing message turns out to be one of five things. They are listed in the order they actually happen, so working down the list is the fastest way through.

1. The alias is switched off

An alias that is off accepts nothing. Mail sent to it is refused at our end and the sender gets a bounce.

• Open your dashboard and find the alias.
• If the switch is off, turn it on.
• Ask the sender to try again. Nothing that arrived while it was off can be recovered, because we did not keep it.

2. Your own provider filed it as spam

This is the most common cause by a distance. Forwarded mail arrives from our servers rather than the original sender's, and some providers treat that as suspicious for a while. Forwarded mail is landing in spam has the fixes that actually work.

3. A rule or a blocklist entry matched

If you have a rule that blocks a sender or a domain, mail matching it is dropped at our relay and never reaches you. Check your rules and your blocklist for anything matching the sender.

4. The recipient address is not verified

An unverified recipient receives nothing. Open Recipients and check for a pending verification, then open the link we sent.

5. The monthly allowance is used up

Forwarding is capped at one gigabyte a month. Past that, mail is refused rather than silently dropped, so senders get a bounce. See The monthly allowance.

If none of those explain it

Write to us with the alias address, the sender's address, and roughly when the message should have arrived. Delivery failures are kept for seven days, so a recent example is something we can actually look at. An example from a month ago is not.