[Dovecot] A few easy pam and virtual domains questions

[Mauricio Tavares]

        Something I forgot to mention: when I first connected to the
mail server as raub using imap, dovecot created a few files. No
problem with that. But they were owned by the user raub,

raub at mail $ ls -la /var/spool/vmail/flingingmonkey.com/raub
total 32
drwxrwxrwx 5 virtual  virtual 4096 May 26 16:23 .
drwxr-xr-x 4 virtual  virtual 4096 May 21 11:34 ..
drwxrwxrwx 2 virtual  virtual 4096 May 21 11:34 cur
-rw------- 1 raub users     17 May 26 16:23 dovecot-uidlist
-rw------- 1 raub users      8 May 26 16:23 dovecot-uidvalidity
-rw------- 1 raub users      0 May 26 16:23 dovecot-uidvalidity.4a1c4fa9
-rw------- 1 raub users    140 May 26 16:23 dovecot.index.log
drwxrwxrwx 2 virtual  virtual 4096 May 21 11:35 new
drwxrwxrwx 2 virtual  virtual 4096 May 26 16:23 tmp
raub at mail $

instead of user virtual, which is the account I have to own
/var/spool/vmail and is known to dovecot as

virtual_uid_maps = static:1500
virtual_gid_maps = static:1500

Why is it doing that? Is that another clue that it think raub is a
local user due to it being authenticated through pam?