Unsubscribed from the list due to too many bounces

[Curious Marc via cctalk]

I have been auto-rejected from the list again, due to too many bounces, 
whatever this means. But I swear I have been a good boy and did not bounce too 
much! This is a plain vanilla gmail account by the way. Does anyone have any 
idea why this keeps happening? Anything I can do about it?
Marc