[exim] Re: MBX format and UW-IMAP

For the record:

The initial problem with the lock appears to be that exim creates
the lockfile in /tmp owned by the exim user and mode 0600.

The c-client code (as used by the UW-IMAP daemon) cannot change its
lock status on the mailbox without first obtaining an exclusive lock on
the corresponding lockfile in /tmp. To do this it needs to open that file
read-write, but the ownership and permissions prevent this. The net result
is that the mail client can no longer access the mailbox.

When the UW-IMAP daemon creates these lockfiles it uses mode 0666, so as
a work-around I have changed the call of chmod() in
src/transports/appendfile.c to set this mode and the problem has gone away.
I just hope that this isn't going to have unforseen side-effects!

Dave