[Mailman-Users] Your membership in the mailing list XYZ has been disabled due to excessive bounces

[James]

 I got unsubscribed from my own list because of "Your membership in the 
mailing list XYZ has been disabled due to excessive bounces". I don't get 
it. I didn't send any emails to the list so how could there be any 
'excessive bounces'.
 Two questions:
 1) Why am I getting this message?
2) Is there any way to prevent and/or protect the list from this happening 
again?
 TIA.