It is possible to autosignature emails wth Maximizer Enterprise 5 or 2000 (which have greatly improved email capabilities over Enterprise 4), but unfortunately not with Maximizer Enterprise 4.
The only way to do this in Maximizer Enterprise 4 is by creating a document template in the Maximizer Word processor which you can later merge to email from the menu File->Merge->To Email. From the File->Merge->to Email option you can choose who to send it to (i,e the current list, or the current entry, etc), and whether to send it in the body of the email (so that it appears as a normal email) or as an attachment.
I Hope this is of some help.
CABC Support
P.S
If you prefer Microsoft Word, CABC's addon "Max Doc" will add the same features into Words menus and is compatible with Enterprise 4.