Aw: RE: convert mdbox to maildir

lutz.niederer at lutz.niederer at
Sun Aug 14 10:24:21 UTC 2022

mdbox is a proprietary format, only dovecot can handle it (afaik).  Postfix can write maildir natively, other MTAs, too.  There are many tools to help in case something strange happens.  I believe that using maildir seems to be not that bad.  And I don't see the real benefits of mdbox.  Maybe with "old" spindle driven devices, you may have a performance benefit, but with SDDs...  If you use the right filesystem, use raid 10....  Yes, it is said that mdbox is performing better.  The largest installations we had with dovecot were about 2k users (maildir was used) and another one had about 3k users (with mdbox), they all have branch offices that are connected to their "home" via some sort of vpn or direct connect by the ISP.  We did not see a real difference between maildir and mdbox, maybe because of the surrounding conditions.  And I believe mdbox may be faster, but we did not have the critical masses to see that.

> Gesendet: Sonntag, 14. August 2022 um 11:47 Uhr
> Von: "Marc" <Marc at>
> An: "Patrick Domack" <patrickdk at>, "dovecot at" <dovecot at>
> Betreff: RE: convert mdbox to maildir
> So? that is why you have this lmtp not? Afaik was mdbox created to solve the (performance) issues with mbox and maildir etc. So I just wonder what the logics is behind chosing maildir current day.
> > Not sure what this had to do with the question asked.
> > You're using mbox, but he is using mdbox.
> > Postfix is unable to write to mdbox itself.
> >
> >
> > Quoting justina colmena ~biz <justina at>:
> >
> > > *My* inbox gets filled with thousands of emails, more or less
> > > commercial content and trivial notifications from shopping online,
> > > and postfix crashes and will not accept new messages if the file
> > > "/var/mail/justina" becomes too large.
> > >
> > > Configuring postfix to deliver the mail to "~/Maildir" solved that
> > problem.
> > >
> > > I still need to configure a sieve or a filter or some nicer
> > > mechanism to clear out messages that are either outright spam or too
> > > old or no longer of interest to me.
> > >
> > > On August 13, 2022 10:00:36 AM AKDT, Marc <marc at>
> > wrote:
> > >>>
> > >>> We need to move all users from one (pretty old) installation of
> > dovecot
> > >>> to a new one.
> > >>> The old one uses mdbox for users' mailboxes and maildir for
> > >>> shared/public mailboxes.
> > >>> The new one must be maildir only.
> > >>
> > >> why did you decide to move to maildir?

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