Hello Tom,
I've just tried it with a Demo Version 4.4.3.3 of Photo Mechanic. I use Thunderbird as my default mail application.
I have not found any settings for an email application in PM.
When I select some pictures in a contact sheet and send them via File -> Send Photos via email I get a popup from Photo Mechanic to
enter the images sizes, the mail addresses, subject ... I checked "Review email in email application before sending" and
pressed OK.
With the "flash"-symbol (Save) you can save or load these settings.
Now I get the send window of Thunderbird with addresses, subject and message filled out. The images are shown in
the attachement window.
BTW you can easily ftp photos via File -> FTP Photos as.
I use Windows XP Home.
Regards
Johannes