Olivier wrote: [...]
means that if the only other reading accesses to a (mbox style in this case here) mailbox are via other dovecot processes everything will be fine?
Yes, but you should be aware there are other processes than Dovecot which can access the mailbox, moreover in a read-write fashion, such as your MDA (procmail, sendmail, maildrop, whatever).
Exim. ^^
You had better teach them to also use dotlock files to be safe.
Sure, it of course does that, it being a write access. Just like one dovecot session deleting a mail from the mailbox would need exclusive access to the thing for that time (and hopefully not utterly confuse the mail clients behind those sessions in the process). I just tested this with our web-mail (Ilohamail) and a reload of the inbox nicely reflects the harsh reality of the mail deleted by the other session.
Regards,
Christian Balzer
Christian Balzer Network/Systems Engineer NOC chibi@gol.com Global OnLine Japan/Fusion Network Services http://www.gol.com/