Hi,
I took a stab at editing the wiki ... the changes disappeared? I guess I was overruled.
The wiki (http://wiki.dovecot.org/LDA) states
-m <mailbox>: Destination mailbox (default is INBOX). If the mailbox doesn't exist, it's created (unless -n is used). If message couldn't be saved to the mailbox for any reason, it's delivered to INBOX instead.
I tried to add a little note that the sieve plugin takes precedence. For example if at the end of the a .dovecot.sieve there is a line like:
fileinto "CompanyFolders.general";
then the -m <mailbox> is ignored. I am not sure about the use of 'stop'.
-n: If the destination mailbox doesn't exist, don't create it. This affects both -m parameter and fileinfo action in Sieve scripts. The fallback is to deliver mail to INBOX.
(typo: fileinto not fileinfo)
My testing shows that if the mailbox does not exist then the mail is rejected like so:
=== Your message was automatically rejected by Dovecot Mail Delivery Agent.
The following reason was given: Mailbox doesn't exist: mail-lists.debian
I like the wiki's solution better.
Jim