Expected result
Should start the mesage with Dear $CustomerName.
We do not use these customer notifications as there is no reason to. It only causes confusion on the customer end and provides them of no useful information.
It does not help us internally either - if somebody emails us with an old ticket number, the intended action is the same as a standalone ticket: the ticket should be automatically merged and (re-opened if applicable) to the most recent article of the same subject.
Please use the default setting and do not send customer notifications of merged tickets. Thank you.
An OTRS admin may want to check the current value of Ticket -> Ticket::Frontend::MergeText.
(Of course I don't know if anyone is actively using this functionality, but I for one do believe that sending such notifications is bad practice--internal changes of this kind do not and are not supposed to directly affect the customer. However, that's a different discussion which should probably go to OTRS Wiki/relevant mailing lists if necessary.)
The text is set to its default message:
Your email with ticket number "<OTRS_TICKET>" is merged to "<OTRS_MERGE_TO_TICKET>".
It would be better to find a way to disable that "inform sender" option by default.
In alternative, I suggest to modify it to:
Your email with ticket number <OTRS_TICKET_TicketNumber> is merged to a related previous ticket. (and see if it works)