Will any new mail received by the Service Desk always create a ticket (unless it's associated with a previous one)? We do get spam, informational emails from vendors, and just mails from uninformed users. There's really no need to create a ticket for everything.
Every message read by your SD's email reader will become a ticket UNLESS you run a de-dup procedure and the email matches as a duplicate to an existing ticket.
You can setup specific circumstances in your Identified/Primary stage that will ignore the request.
you can also add a spam filter file that will take the subject and filter out the email based on the subject line content matching the values in the text file.
Email Reader Spam Filter: \kaseya\kserver\ignoresubject.txt
anyone have an example how to delete / keep a ticket from being made if the email subject already exists?
If you're using SD you can build de-duplication procedures that will ignore ticket requests (via email or alarm, not portal entry) based on certain criteria, within a certain time-frame.