[Dovecot] Permission denied changing to mail directory

[Chris Hogan]

I have 3 domains using one mail server. I've set the dovecot mail 
directories to be

/mail/mail/%d/%n

When someone logs on, dovecot attempt to navigate to the domain 
directory first & we get a permission denied, and we get no further. Its 
very odd because (a) it was working up until 16:50 on Thursday & (b) the 
directories now have 777 access. Each user is (at present) a separate 
unix user & the directories are owned by root & have a file group of mail.

I would have thought that the 777 access would have been enough. I don't 
know what we did on Thursday evening, but any ideas about how to fix the 
permissions problem?

Chris