From: Wesley W. Terpstra (wesleyterpstra.ca)
Date: Mon Apr 21 2003 - 16:00:11 CDT

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On Mon, Apr 21, 2003 at 04:30:19PM -0400, Wietse Venema wrote:
> Wesley W. Terpstra:
> > For example: an email spam filter which keeps stastics based on word
> > frequency. Many forms of filtering need a database.
>
> This hasn't been a problem sofar. With typical use, the largest
> file manipulated upon mail delivery is the mailbox, which can be
> several megabytes large. For example, my vacation.db file is only
> 327kb, well under the size of my average mail folder.

True, but there are situations where it could be larger.
Seeing that it is a 'mailbox limit', admins sometimes set it to 10Mb.

That is my main concern really; sure it limits the mailbox, but it also
limits other stuff. Were I to configure postfix, I would probably consider
this as a cap on the files in /var/spool/mail (which is a seperate
partition). I wouldn't stop to consider what my users did in /home.

> The Postfix local delivery agent is written primarily for UNIX
> accounts.
>
> The request talked about a database, something that I would not
> immediately associate with something that runs under control by
> ordinary users.

Ahhhh, I was considering libdb4 (for example) as a database.
I didn't mean an SQL server or something.
You are correct; I should have been more specific.

> If the default Postfix 50MB file size limit is problematic, then
> I wonder about the impact this beast will have when run under the
> control of users.

A good example of a legitamite use would be a user who makes a threaded
keyword search database for all the emails in all of his folders. Each
folder is under 50Mb, but he has say ... 4. At 40% of the text indexed, his
index is now oversize. (and keyword search databases can be updated with a
single seek if done intelligently -- ie: negligible impact)

This is actually the situation I was in. It took me some time to figure out
why my indexer kept crashing too! :-)

> I am not too worried about users storing their personal email as
> a gazillion files of microsocopic size. If someone wants to hose
> the file system then they don't need an MTA to do it for them.

Then too you shouldn't be concerned about users attempting to undermine
the soft rlimit. That was my only point. If someone wants to defeat the
restriction, they can; the hard rlimit just discourages legitamit use.

> What about having separate Postfix parameters for hard and soft
> limits.

I find this is perfectly acceptable.

Just don't call the hard-limit a mailbox size.
Something like 'global_file_size_limit' or something that makes an admin
stop to consider what he is configuring.

Thanks again!

PS. Sorry for the confusing CC's. I thought you didn't get the message
originally due to your email bot which told me to post to the list.

--
Wesley W. Terpstra <wesleyterpstra.ca>

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