Rules

A rule is a condition and an action, evaluated when mail arrives for an alias.

Match on sender or subject, then forward, drop, or send somewhere other than the usual mailbox.

What they are good for

• Sending one alias to a different mailbox than the rest of the account
• Dropping the specific newsletter that ignores unsubscribe requests
• Routing anything from a domain straight to a mailbox you check less often

What they cannot do

Rules never see the message body. Only the sender and subject, because those are what we need for routing anyway. A rule that matched on body text would mean reading your mail on every delivery, and we do not want to be able to offer that.

If you want body-level filtering, do it in your own mail client, which is already reading the message and is the right place for it.

Order

Rules run in order and the first match wins. Put the specific ones above the general ones, or the general one will swallow everything.

Pattern matching

Matching runs with a bounded timeout. A pattern that would take too long is abandoned rather than allowed to hold up delivery, so a badly written rule delays your mail rather than stopping it.

Something here wrong or missing? Tell us. These pages live in the same repository as the code, so a correction is a one-line change.