We have a list of users who no longer have mailboxes in our Exchange environment. We want to have a very specific reply to these users with a possible custom variable.

I thought Postfix would possibly work for this. When it gets a message, it should:

  1. If address is in list: Automatic reply with a bounce-back message (or just a normal e-mail). Message should include a new address; maybe have a database table that translates the old address to new address?
  2. If address is not in list: Send it to exchange.example.com mailhost.

Anyone done something similar and could give me an idea of how to accomplish this?


You may use check_recipient_access to specify access map/table with custom reject messages for some recipients e.g.

jane.doe@example.net  551 User has moved; please try jane.doe@example.com

You may use the above to accept messages to listed valid recipient (see DUNNO access action), reject messages to "moved" recipients with custom message, reject messages to non existing recipients.


  1. The above solution rejects recipients in SMTP session. Your server does not generate bounce message itself, they should be generated by servers sending you messages. The message may be "cryptic" or masked by email reader of the sender.
  2. You may "advertise" new addresses to spammers.
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