Re: [9fans] Setting up Mail in Acme on the Raspberry Pi.

[Bakul Shah <bakul@bitblocks.com>]

On Mon, 13 Oct 2014 12:15:31 EDT erik quanstrom <quanstro@quanstro.net> wrote:
> On Sun Oct 12 14:37:47 EDT 2014, steve@quintile.net wrote:
> > I am fairly sure the problem is to do with RAM size rather than the ras=
> pberry pi per-se.
> > 4000 messages takes up a lot of space - and upas stores messages in RAM=
> .
>
> it's a little worse than this, actually.
>
> since upas stores messages in mbox format, the whole file needs to be rea=
> d or written on
> update.  certainly one could optimize the read bit, but that would be dif=
> ficult  this means
> that the the whole mbox gets written to the dump every day, and you need =
> about 2x the
> mailbox size ram for each upas/fs that is run.  this does not work out we=
> ll for large mm
> messages, or small ram boxes like the pi.
>
> the solutions to this are straightforward
> (1) store one message per file,

This is what MH (an old mail client) does by default.

> (2) cache important data in an index to avoid opening all files,

This is what dovecot (an imap/pop3 server) does.

One other thing such mailservers do is to usually only
*append* to an mbox file. Deleted messages are marked as such
but their space is not reclaimed until you force a rebuild of
the mbox file and its index.

Pure imap clients typically only read last N messages from a
given mailbox.  More may be loaded as you scroll back.