Re: [exim] Local senders whitelist: practical limits

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Author: Mike Cardwell
Date:  
To: exim-users
Subject: Re: [exim] Local senders whitelist: practical limits
* on the Thu, Jan 25, 2007 at 03:50:12PM -0500, Rob Munsch wrote:

> Due to increasingly fascist local antispam policies, we are of course
> bouncing a lot of people's mail. Such people are invariably the friends
> and/or business contacts of Important People in the office.
>
> I'm using an
>
>    accept
>      senders = lsearch*@;/etc/exim4/local_whitelist

>
> before my ACLs start getting nasty, which a flat file containing the
> addresses of People Who Should Never Be Blocked. But naturally now that
> the existance of this file is known, everyone wants in on it. One
> enterprising department forwarded me a spreadsheet of 2000 addresses
> "who we never want to get bounces," most of them from @gmail.


I'm afraid I'm not going to directly answer either of your queries, but
offer an alternative solution that I use, and might help instead. You
can still have your static file whitelists, but on top of that you can
dynamically generate a whitelist as well. I do this by using an sql
database. Every time someone from your office sends an email to someone,
add that destination address to a whitelist table in the db, and accept
all future emails from that address.

Also, when an email comes into someone at the office, record the sender
in a separate table with a counter of the number of times that person
has sent an email. Then you can whitelist addresses that have emailed
one of your colleagues more than twice for example.

You could populate these tables with historic data by processing your exim
logs, for an immediate win.

The overhead caused by the SQL queries on my system is more than offset
by the fact I don't do any spamassassin filtering on whitelisted
addresses.

Mike