My printer preferences don't have an A7 envelope option in the drop-down menu through InDesign CS3 (or any other program for that matter). I'm on an iMac Intel Core 2 Duo running OS 10.5.8.
I've tried using the Xerox support forum, but they don't seem to know much about InDesign. PC's have been able to print envelopes, just having issues with my Mac…