If you use the Mailconverter and want to manage your Tickets you will have some problems in VtigerCRM 6.1 if you use the build in “has Ticket Number” Rule.
That's why this condition had two Bugs.
At first the Subject isn't recognized correctly and the second one is the wrong check if this rule have matched to a Ticket.
To fix this take this two modifications:
$match_string = $matchinfo['matches'];
if($match_condition == 'Has Ticket Number' && $match_string) return $matchinfo;
$searchfor = "^Ticket Id[^:]?: ([0-9]+)$";
$searchfor = "Ticket Id[^:]?: ([0-9]+)";
Now the Ticket System should work as expected!