[Dovecot] Autocreating INBOX only

[Edgar Fuß]

I would like deliver not to automatically create subfolders for mails  
addressed to [EMAIL PROTECTED], but nevertheless  
automatically create INBOX for new users. I'm not sure whether a new  
option like -M or -m -m would be appropriate, i.e., whether anyone  
needs the current -m behaviour.

It looks to me like one would need to change  
mailbox_open_or_create_synced()

        if (box != NULL || no_mailbox_autocreate)
                return box;

to something like (assuming an enum mailbox_autocreate 
{_never,_inbox,_always}

        if (box != NULL)
                return box;
	if (mailbox_autocreate == mailbox_autocreate_never || strcasecmp 
(mailbox, "INBOX") != 0)
                return NULL;