[Dovecot] Locking strategy?

[Gerhard Wiesinger]

Hello!

I run the following environment:
UW imapd
pine
sendmail
procmail
mbox format

I migrated from UW imapd to dovecot. It is pretty faster than UW imapd.
To ensure a compatible environment I did the following configuration 
changes in /etc/dovecot.conf:

protocols = imaps

default_mail_env = mbox:~:INBOX=/var/mail/%u

mail_full_filesystem_access = yes

mbox_read_locks = fcntl
mbox_write_locks = fcntl

But I don't think that locking works well. In pine I get the following 
error messages:
Unexpected changes to folder (try restarting)

Also when I delete a file in the imap inbox I can't see that immediatly in 
pine (even when I restart pine the message is still there with a "Deleted" 
flag.

With UW imapd locking worked perfectly but performance was very bad.

What is the best configuration in a dovecot/pine/sendmail/procmail/mbox 
format environment.

Thank you for the answer.

Ciao,
Gerhard