I installed and then setup the new osTicket.
Filed a test ticket and the email sent had this in it:
You can view this ticket's progress online here: e=dave@mydomain.com&t=207572" target="_blank">http://www.mydomain.com/support/view.php?e=dave@mydomain.com&t=207572(http://www.mydomain.com/support/view.php?e=dave@mydomain.com&t=207572).
Looks like either the message template or the processing has an html error it when sending to some mail hosts.