Routing Priority

Routes are strictly checked by their index, in descending order. The highest number is checked first. As soon as a route matches, the selection is complete.

Terms

• Index: Integer used to sort routes. A higher index is checked first.
• Pair: Combination of sender and recipient from the SMTP session. Sender = Envelope MAIL FROM, Recipient = RCPT TO.

Rules

1. Order: Routes are checked per pair in descending index order. Highest index first.
2. Uniqueness: Exactly one route applies per pair. After the first match, no further checking is performed.
3. Multiple recipients: With multiple RCPT TO entries, a separate pair is formed for each recipient and routed independently.
4. New routes: New entries automatically receive the lowest index and are therefore placed at the end. Afterwards, move them to the desired position or set the index manually.