Hello, we use smtpd_sender_restrictions on our outgoing smtp gateway to filter mails from users who are not allowed to send mails to external recipients. We use the following config:
smtpd_sender_restrictions=check_sender_access hash:/etc/postfix-outbound/sender_restrictions, check_sender_access regexp:/etc/postfix-outbound/sender_nice_reject.db The sender_restrictions file contains a list of valid mail addresses exported from our active directory in the following form: daniel.fiederl...@warema.de OK The sender_nice:_reject.db contians only the following line to generate a custom error message: /./ 554 Sie duerfen keine eMails nach Extern senden, bitte wenden Sie sich an die IT Hotline. / You are not allowed to send mail to external addresses, please contact the it hotline. Our problem is that we offend rfc complaince because those filtering rules prevent internal generated non delivery reports to be sent out to the sender of the failed message. How can I weaken the filter to achive NDRs being sent out? I tried regular expressions in sender_nice_reject.db like these without success: /^\<\>$/ ok or /^$/ ok Any help or pointers are appreciated. bye Daniel