Eiltesir
Emails will always thread through existing Tickets if it contains the appropriate information. Just like typical mail providers, we look for specific Headers that reference an existing thread/email. In order to thread, the incoming email must contain a valid In-Reply-To and/or References header. If not, we look at the message-id to see if we can decode it and if it was created by our system we will be able to match it accordingly. Lastly, we check for the Ticket Number in the Subject of the email.
If the mail doesn't contain any of this information there is no way the system can know what the email was intended for and therefore creates a new Ticket.
Cheers.
