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PostFix Sender-based Routing

If you want to use a more fine-grained model you can choose to relay the outbound traffic for domains over separate users. This allows you to apply different settings per domain, but also provides the end user access to their own logfiles.

  1. Create sasl_passwd file for the individual outgoing user(s):
  2. @example.com outgoing@example.com:THEPASSWORD

  3. Create the sender_relay file
  4. @example.com [SMARTHOST1]:587
    @example.net [SMARTHOST2]:587

  5. Postmap both files:
  6. postmap /etc/postfix/sasl_passwd
    postmap /etc/postfix/sender_relay

  7. Add the following to your main.cf:
  8. relayhost = [SMARTHOST]:587
    smtp_sasl_auth_enable = yes
    smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
    smtp_sasl_security_options =
    smtp_sender_dependent_authentication = yes
    sender_dependent_relayhost_maps = hash:/etc/postfix/sender_relay

    The above extract also configures server-wide, to ,also filter those that are not added on the sender_relay file. If you do not want this and only want to filter specific domains remove the relayhost line from above

  9. Restart PostFix.