This is still an early release - use at your own peril, please do setup a totally separate email account!
This version changes actions the add-on will take to simply change the state of the user to
Bouncing emails in XenForo 1.3, or
Awaiting confirmation (from edit) in older versions.
The add-on now supports IMAP and POP3, however is a twist of fate I've only tested the IMAP support in this version.
Also, the add-on now supports selecting which bounce states are treated as a permanent failure and therefore cause the user's state to be changed.