[tor-relays] "excessive bounces" on tor-relay list

Hi, I keep getting the warning once in a while that there are excessive bounces from my email address and that my membership to this list has been disabled until I click on a link to re-enable it. Is there any reason why something like this would happen? I use yahoo mail, as you can see but I just don't know why Yahoo Mail would bounce any message. I have not received any warnings from Yahoo about such an action. Thanks, -kali-