Sorry if this is a simple answer but I could not find anything on google about this.  I keep having to reconfirm my membership with this list because I assume google is kicking back messages.

Message is as follows:
Your membership in the mailing list Users has been disabled due to
excessive bounces The last bounce received from you was dated
21-Jan-2014.  You will not get any more messages from this list until
you re-enable your membership.  You will receive 3 more reminders like
this before your membership in the list is deleted.

To re-enable your membership, you can simply respond to this message
(leaving the Subject: line intact), or visit the confirmation page at