FatherBear,
This isn't enforced by s2Member, it's enforced by WordPress itself.
If you have a GMail account and you're adding all these s2Member accounts yourself, here's a way you could solve this:
GMail allows you to create aliases "on the fly" by simply adding a plus symbol and then an extra word. For example, if your email address was
fatherbear@gmail.com, you could use a different address for each account like this:
fatherbear+bob@gmail.com,
fatherbear+joe@gmail.com,
fatherbear+kate@gmail.com, etc.
Any email sent to those addresses will simply go to your
fatherbear@gmail.com account. (If you want to filter out those emails in GMail, you can set up a filter that checks for the full To address and moves it to a separate tag.)
Does that sound like it will work for you?