Hello dear community,
here's the problem:
There are no end-user emails sent (e.g. when the user sends a mail and a new ticket is created in the system).
Configuration:

Explanation:
aaaa@a.de is a real existing mailbox from which the mails are retrieved and sent.
bbbb@b.de is a pure forwarding (i.e. without a mailbox behind it), which forwards the mails to aaaa@a.de. So far it works as well.
For the user only the bbbb@b.de address should be "visible".
The user therefore writes to bbbb@b.de, which is forwarded to aaaa@a.de.
osTicket picks up the mail, creates a new ticket and notifies the internal agent, but not the user.
If the mail goes directly to aaaa@a.de, the user is notified.
I suspect that this is somehow related to the fact that the mail from the user has bbbb@b.de in the to: row and osTicket has a problem with that.
Can you help here? Did I set a setting wrong?
Thanks a lot for the answers!
Many greetings
Jochen