[Dovecot] plus addressing bug in dovecot 1.1.x?

[Jon Fullmer]

I had recently upgraded from Dovecot 1.0.14 to 1.1.0, and then to  
1.1.1.  Ever since the upgrade to 1.1.0, I noticed that "plus  
addressing" has failed. In case I'm using a foreign phrase, this is  
the concept of sending an e-mail to "user+spam at domain.com", and having  
dovecot (dovecot LDA, specifically), deliver this to the "spam"  
submailbox to "user at domain.com". I've been using this successfully  
since 1.0.3.

When I upgraded to 1.1.0, I noticed that e-mails were no longer being  
delivered to the submailboxes as they had been (though they would  
arrive in the central INBOX). I checked the "dovecot-deliver.log", and  
I noticed that, ever since I had brought up 1.1.0, I would see:

save failed to spam: Unknown namespace

("spam" is the submailbox)

After the upgrade to 1.1.1, I still would see these messages (and  
behavior). I have since installed 1.0.15. The plus addressing now  
works again, as it had been.

With all of these "upgrades" and "downgrades", the config file has  
remained exactly the same. There have been no other changes to any  
components on the host system (i.e., new OS-es, new postfix, etc.).

Thoughts? Is this a known issue?

  - Jon