Using Ubuntu Karmic and Firefox 3.5.6.
Following advice here:
to default to pdf/A4 when printing to file in firefox.
#!/bin/sh firefox -remote "openurl(https://mail.google.com/a/YOUR_GOOGLE_APPS_DOMAIN_HERE/mail?view=cm&tf=0&to=`echo $1 | sed 's/mailto://'`,new-tab)"