Messages on different mail addresses are merged into one ticket

Infos:

Used Zammad version: Zammad 6.0.0-1691946056.47e1e571.focal
Used Zammad installation type: Deb package
Operating system: Ubuntu 20.04.6 LTS
Browser + version: all

Expected behavior:

A company has multiple divisions:
Division A has email address sales@company.com
Division B has email address accounting@company.com

Each division has its own group in Zammad with the address configured.
When a client sends an email to a division address, a ticket should be created for the respective group, or if the group already has one, new article should be added to it.

Actual behavior:

A client sends two separate emails, one for each division: first for division A, then for division B. The subject field may be the same, for example something like “My order”.

Both articles will be created on the same ticket, in this case for division A (or whomever got the email first).

Are those two mails, apart from the recipient, identical?

No, the body is completely different. The subject is the same.

Does this still happen if you upgrade an up to date Zammad 6.2?

I will check after i do the update.
Thank you.

Yes, the problem persists.
An email that was originally sent to a one division was manually resent by our senior director to another division. The article has been assigned to the same ticket that it was before, the recipient staff has no access to this division - this was the reason for resending it.

What exactly do you mean by “resending”?

I apologize for the confusion, by “resending” i mean forwarding an email to another recipient.

We’re facing similar problems since a couple of months. It rarely happens and i didn’t figure out how to force this behaviour, so we used to ignore it, but i seem to have found out how i can recreate it.
If i forward an email that created a ticket earlier and use the identical subject, without any Ticket ID in the subject, Zammad will merge that new email into the initial Ticket that got created from the email that i forwarded.

Some of our users have reoccuring tasks for our department that are very similar. Often they just forward an email they sent weeks or months ago and make slight changes in the body of the email. Unfortunately their emails reopen old tickets unintentionally and won’t create new ones.

That behavior is intentional.