Dbox and Exim

Timo Sirainen tss at iki.fi
Wed Oct 15 03:18:57 UTC 2014

On 10 Oct 2014, at 00:53, Andre Rodier <andre at rodier.me> wrote:

> On 09/10/14 23:06, Timo Sirainen wrote:
>> On 09 Oct 2014, at 15:20, C Peters <chuck.peters at gmail.com> wrote:
>>> The Dovecot wiki [1] doesn't list either Exim, Postfix or anything
>>> else as supporting the dbox.  I did some searching in the Exim
>>> archives and have found only one message mentioning dbox, sdbox or
>>> mdbox. [2]  I think an RFC would go a long way towards getting the
>>> format supported.  Has Timo, or anyone else, considered submitting an
>>> RFC to the IETF?
>> No, and I don't want it to happen anytime in near future. The dbox format is highly Dovecot-specific, because it relies on Dovecot's index files. These index files are still changing and I'm not sure if they will ever be fully finished. I don't want any other software to even attempt to implement the same functionality.
> I am sorry if I am presumptuous or out of topic, but it seems to me that the mail storage should be standardised.
> I am still using Maildir myself, simply because I like the simplicity, one file is one email, one directory is one email folder, for backup or restore.

Sure, mbox and Maildir are pretty standard. And Maildir is especially good if you care about reliability more than performance. But dbox was especially designed for performance - trying to standardize it in any way would limit the ability to improve its performance in future. So dbox isn't really meant for people who want to use any kind of a standard, it's for people who want as good performance from Dovecot as possible.

> A feature I would like, is dovecot being able to store emails in databases, SQL or NoSQL. I would use this for archiving and queries purposes. MariaDB / Drizzle, or MongoDB, CouchDB, etc. There is plenty of choice.

Dovecot's (commercial) object storage plugin could probably be used with NoSQL servers. We've been looking into Cassandra support at least.

> Maybe this storage scheme would be slower, but IMHO, this is not a problem when people just want to archive their emails on a remote computer.
> Maybe I could start this if I had some template or example to start.

There's a very old SQL storage plugin for Dovecot. It would require a lot of work though:


There is actually also a working read-only SQL storage plugin that supports only INBOX. I could send the sources for that as well.

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