Something I don't understand...rant to follow.
If you change your email address, why don't you just let everyone you know know about it?
I use www.plaxo.com as an effective way to keep track of people, but all I'm saying is if you change from @comcast.net or whatever to @yahoo.com or @gmail.com, just send out an "hey, I've changed my email address" so that I don't get an error message.
Otherwise, it sends the message of "I don't care enough about you to tell you what my new email address is" or "I don't want to hear from you anymore."
Both of those are possibilities, of course, but just be a man (or woman) about it and break up with me directly. Don't make me guess when I get a bounced email.