[Mimedefang] MAX_RCPTS_PER_MESSAGE replaced by Milter?

David F. Skoll dfs at roaringpenguin.com
Mon Sep 24 14:56:10 EDT 2012

On Mon, 24 Sep 2012 13:45:38 -0400
"Kevin A. McGrail" <kevin.mcgrail at mcgrail.com> wrote:

> Anyone ever gotten rid of MAX_RCPTS_PER_MESSAGE at the sendmail level 
> and implemented this programmatically with MD?

We use whatever Sendmail's default is for MAX_RCPTS_PER_MESSAGE
(I think 100, or perhaps unlimited?)

> My thoughts are to have the standard limit but raise it for 
> authenticated users and/or perhaps give them more of a rate or per
> day limit?

Those are two very different things. :) Limiting the number of
recipients per message is not terribly hard; in filter_recipient you'd
just increment the count and tempfail once the limit is reached.  The
only wrinkle is that you'd have to store the count in a file in the
current working directory because you're not guaranteed that
filter_recipient is always called in the same process as the previous
filter_recipient call.

Implementing hourly or daily limits per sender *definitely* requires
persistent storage; it has to persist with filesystem lifetime so
you're probably looking at a database.

In our commercial product, we offer the ability to limit the maximum
number of recipients per hour per sender or per sending IP address
with a choice to fail or tempfail after the limit is hit.  We have to
use a database to track this.



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