Is your group configured to open new ticket supon follow ups on closed tickets?
Because that’s imho the only reason why Zammad would do the described action - beside of someone removing all references.
The weird part is previously the ticket didn’t recreate with the setting above. We also don’t want to reopen ticket when customer do auto reply or courteously reply it.
Is there an alternative way or setting where it does not create the ticket?
“do not reopen ticket but create a new ticket” will always create a new ticket on any follow up on that ticket. It doesn’t matter if it’s a message coming in via CC or direct TO.
There’s currently no way to ignore follow ups entirely.
Technically this never should have worked differently, if you didn’t change the above mentioned group setting earlier.