[svlug] Exim on Red Hat 8.0

Ian Kluft ikluft at thunder.sbay.org
Tue Jan 7 17:46:11 PST 2003


>From: Greg Herlein <gherlein at herlein.com>
>> > I didn't have any major complaints with Sendmail. Sendmail has run well for
>> > me. I just wanted to try out exim. My initial impressions are quite
>
>What are the compelling arguments to switch?  If my sendmail is
>working fine, what advantage(s) are there to converting?

If everything is working fine, frankly you're in no need to hurry to switch.
But to answer your question, here are some reasons why I prefer Exim...

* Exim was designed with modern security issues in mind.  Sendmail is a
  direct descendent of 1980's code.  For some, Sendmail still carries scorn 
  for an infamous history of security blunders all the way back to when it
  was the primary entry vehicle for the Morris Internet Worm of 1988,
  which shut down the Net.
* You can block connections from hosts which don't have a reverse DNS entry.
  This was one of spammers' earliest "tricks" to hinder efforts to trace
  them.  But most still use it.
* It has excellent control of mail relaying (relay only for domains you
  own/host) and native support for realtime blocking lists "RBLs".
* Messages can be filtered for spam and viruses while the remote host is
  still connected - rejecting them at this stage forces the spammer to
  store it on their disk, not ours.
* Configuration files are readable without a macro preprocessor, giving you
  direct access to all its features.  (Exim started in 1995 as a ground-up
  rewrite of Smail, and mimics this strength of Smail.)
* The configuration can be very powerful - I use it to run MailMan lists
  for several domains.  i.e. Exim uses Mailman's configs to detect mail
  lists - I don't have to touch Exim and it uses a new list immediately.
* Before Sendmail had "milters" (mail filters), Exim allowed embedded Perl.
  Marc Merlin used this feature to embed the perl-based SpamAssassin in
  Exim with his SA-Exim package.)  However, Perl is not required if you
  wish to optimize for performance - Exim's other features remain.
* You can use string expressions and database queries to make very powerful
  mail routing.  You can optionally embed PostgreSQL or MySQL.  Or just
  use DB/GDBM/SDBM.
* Mail routing and delivery can be controlled using separately-configured
  so that you can write new ones with or without programming...
  "routers" - control of handling of an address' host/domain
  "directors" - control of handling of an address' local target
  "transports" - delivery mechanisms to files, network, scripts, etc

I could go on.  That's off the top of my head.

For more info see http://www.us.exim.org/



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