Your web page says the MailCOPA email program works with the AVG7 virus scanner, but I use a virus scanner from another company, will it be compatible?

This is actually a question you should ask your virus scanner manufacturer.  But the answer is almost certainly, yes.

Most virus scanners intercept email as your email program downloads or sends it.  The email client installed does not even know it is doing this.  If your virus scanner is of the intercept variety, and almost all are, then it will work just fine with MailCOPA.