Ok - at this time I am using the following non-default settings:

Samba server - smb.conf [Mailstorage] ea support = Yes use sendfile = Yes fake oplocks = Yes delete readonly = Yes

Dovecot - dovecot.conf mmap_disable = yes dotlock_use_excl = yes fsync_disable = yes lock_method = dotlock

I'm still testing - but at this time I'm seeing no errors.

Two options I can state cause severe problems are the "directio" and "setuids" mount options for the cifs client.

Daniel