[Dovecot] plus-address delivery

[Jon Fullmer]

Forgive me, if this has been previously discussed. I researched as  
best I could. I couldn't find anyone mentioning it.

Please treat me as a newbie.

I've recently set up postfix, amavisd-new/SpamAssassin, and dovecot.  
All three utilize a user database in a MySQL db (on the same host). So  
far, so good.

The problem:  I wanted amavisd-new to deliver an e-mail above the  
"$sa_tag2_level_deflt" to the spam mailbox inside each user account.

To accomplish this, I've instituted (best as I can tell) "plus  
addressing." The idea, if I have this correct, is that if a spam  
message is being sent to "<user>@<domain>.<tld>", amavisd-new will  
change the receiving address to "<user>+spam@<domain>.<tld>". The  
"+spam" will translate to the mailbox named "spam" within the  
structure of "<user>"'s mailbox.

I think the important lines from the amavisd-new config are:

@addr_extension_spam_maps       = ('spam');
$recipient_delimiter = '+';

Long story short, (too late) the e-mails are being delivered, but to a  
completely new mailbox called "<user>+spam".  For example, when I list  
the directory "<domain>.<tld>", I now see two mailboxes (as opposed to  
one): "<user>" and "<user>+spam".

Is there something I need to configure within dovecot to have it  
recognize "plus addressing", or should it do so by default?  I'm  
certain I've just missed something really simple.  Any thoughts would  
be appreciated.  Thanks!

  - Jon