Problem: After setting up my e-mail account in Thunderbird on a new machine, Thunderbird is adding my e-mail address to the recipient list every time I do a Reply to All. So every time I do a Reply to All I get a copy of the message.
This is on a Mac running Mavericks, OS X 10.9 but should apply to Windows or Linux as well.
Solution: The answer is pretty simple. If you go to Tools -> Account Settings and select your account, your e-mail address and name are listed in this form. If the name in this form does NOT match your actual e-mail address you get the behavior described above. In other words, you have a typo in your e-mail address. Fix the typo and everything should work correctly.
That is a a subtle one. Hope this helps others with fat fingers like me.