dragging an old thread back here...but i have the exact same problem. getting 'over quota' errors (Virtual Users And Domains With Postfix, Courier, MySQL And SquirrelMail (Debian Lenny)) but adjusting the db value does nothing
current maildir size is about 110mb, i've raised the limit to 1gb (6gb free space on server)
the strange thing about this is that i can still receive emails, i just cant move them to my other imap folders
any suggestions? have updated everything, done the postfix quota patch, increased the value in the db...
i would have thought if my setup wasn't working that other parts would be failing?