[Dovecot] Possible bug: why is the owner of home-directory important?

[Qweb - Yavuz Aydin]

Dear all,

I am trying to migrate one of our systems to dovecot. We were using uw-imapd in
black-box-mode before. Since the home-directory of a user is not unique per
definition on our systems, we have kind of a different setup.

As an example:
I got a user, let's say user1. It's home directory is
/local/web/websites/5850844095/www. This directory has the following
permissions:
# ls -la /local/web/websites/5850844095/|grep www
drwxr-x---   7 www-data g5850844095 4096 Oct 13 12:28 www

(user1 is member of the group g5850844095)

Why is logging in not working properly? See:
# telnet localhost 143
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
* OK dovecot ready.
1 LOGIN user1 password
1 OK Logged in.
Connection closed by foreign host.

And in the logfile I see:
Oct 13 13:09:47 s1 dovecot: chdir(/local/web/websites/5850844095/www) failed
with uid 1020: Permission denied
Oct 13 13:09:47 s1 dovecot: child 1527 (imap) returned error 89

However, when I change the permissions on the home-dir to 755, it works. The
point is, none of my mailboxes (INBOX or others) are in my home-dir, so why
does dovecot need my home-directory?

I hope someone can help.

PS1 the default_mail_env reads:
default_mail_env = mbox:/local/mail/imap/%u/:INBOX=/local/mail/spool/%u

PS2 This is on a Debian Sarge (3.1) system.

-- 
Best regards,

Yavuz Aydin
Qweb Internet Services