Infinite feedback loop on fake customer e-mail


  • Used Zammad version: 6.1.0
  • Used Zammad installation type: docker-compose
  • Operating system: Linux (Linux 5.15.0-88-generic #98-Ubuntu SMP x86_64 x86_64 x86_64 GNU/Linux)
  • Browser + version: Firefox 120.0.1 (64-bit)

On creating customer with non-existing e-mail and updating ticket (with that person as a customer) infinite loop is created

Actual behavior:

  • Zammad calls linked SMTP server for e-mail update
  • Mail server (Postfix) tries to send an e-mail to non-existing address, fails, returns to Zammad
  • Zammad automatically creates a new ticked based on e-mail send failure, then tries to notify non-existing customer about failure once again which results in a feedback loop

Deleting all customers with fake e-mail addresses helped break the loop

Steps to reproduce the behavior:

Linking Postfix server in Zammad E-mail configuration
Creating customer with a fake e-mail
Creating a ticked with that customer

Is there a way or a setting to prevent Zammad automatically create tickets when e-mail sending is failed or should it be done within mail server rules?


Ignoring NDR mails in my very humble opinion is the worst way to approach this.
Because: You won’t notice when you’re writing to a non existing mail address and that’s a bad situation.

Zammad has a “Block notification” setting which imho is the better approach as it also affects triggers technically: