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I think a nice feature would be to have an audit trail of who is getting emailed and why. It would help to track down issues with who is and isn't getting certain notifications. Just a running log in the log menu that lists the emails going out and the reason...
11/25/13 - 5:11pm - [email]email@example.com[/email] - Ticket 12345 - Transfer Ticket - Helpdesk Team Member
11/25/13 - 5:01pm - [email]firstname.lastname@example.org[/email] - Ticket 12345 - Assign Ticket - Helpdesk Team Member
11/25/13 - 4:59pm - [email]email@example.com[/email] - Ticket 12345 - New Ticket Creation - Ticket Creator