Re: [Exim] MH mailbox format

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Author: Nigel Metheringham
Date:  
To: John Horne
CC: Exim Users List
Subject: Re: [Exim] MH mailbox format
J.Horne@??? said:
> Just wondering why Exim seems to support maildir/mbx/mailstore mailbox
> formats, but not MH? The software itself seems to still be in
> development - my first thought was that it was not used any more. I'm
> trying to sort out a small problem with an MH mailbox, and will use
> procmail.


Despite being a long time user of MH, there are *serious* problems with
the MH mailbox format which make it a pig to support, specifically:-

  1. message filenames are incrementing numerics, however there is no
     defined means to lock the directory so that 2 delivery processes
     do not hit the same filename.  Although exim can solve this
     problem for itself, other tools need to use the same locking
     protocol (and for MH they don't use any)


  2. The unseen sequence should be updated on delivery, however this is
     fairly deep magic and involves updating another shared file with
     no defined locking protocol.


MH is a real problem for an MTA, so its better to skip it and leave it
to an MDA such as rcvstore (note this doesn't do locking either, so if
you use procmail you should have a per folder/directory lock file to
prevent collisions which really *do* happen - I've seen them.

I like MH, and *really* like exmh, but am likely to change store
formats soon to something saner.

    Nigel.
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[ Nigel Metheringham                  Nigel.Metheringham@??? ]
[ Phone: +44 1423 850000                         Fax +44 1423 858866 ]