Email links in templates

All:

I have the following line in a custom template:

mailto: rt_{$Ticket->QueueObj->Name}_comment@domain.com?Subject=[{$rtname}%20#{$Ticket->id}].

Certain email clients will not display the email address as a link.
Is there a way to absolutely be certain that a client will see HTML
messages, or at least the mailto link?

Any suggestions would be appreciated.

Dave Long
long.dave@gmail.com