I've been experimenting with relocated_maps as well as user-specific entries in transport_maps. They work, but they also terminate the SMTP conversation with the defined message. In my configuration the sender would never see that message because the mail is received by the external spam filtering service, then forwarded to the local server which serves as the final destination for the domains.
So I'm wondering if it would be possible to accept the mail, blackhole it, and send a bounce-message to the sender with a "User unknown" message. User-specific blackholing seems to be easy to implement, but how about the "user unknown" bounce message? I'd like to be able to "actively notify" (with a bounce) the sender about non-existence of some old accounts. Thanks for the insights! Ville
