sendmail cluster

Peter Mueller pmueller at
Tue Jul 27 18:07:39 BST 2004

Sorry about breaking format, I'm using webmail.  I would like to go inline but with this it's such a chore..
MTA : use what you are most familiar with.  Like Todd I'm also most familiar with Postfix and Sendmail; those are the two I like most.
The part I'd like to chime in on is the remote file mounts.  Although you could buy a SAN or setup NFS, you will most likely end up setting a single-point-of-failure that will bite you down the line.  Maybe a combination of SAN/NFS with DRDB ( would be appropriate.
Then again, maybe we are all batty.  You haven't said how much traffic you expect or what kind of budget you are working with.  Until you do, we'll probably keep adding more and more fault tolerance to your setup.  Pretty soon you will have 50 servers for this mail setup formerly handled by one.


From: lvs-users-bounces at on behalf of Todd Lyons
Sent: Tue 7/27/2004 8:26 AM
To: users mailing list.
Subject: Re: sendmail cluster

Omar Armas wanted us to know:

>I want to setup a cluster for a high load mail service.
>Currently I have one single server with debian, sendmail, qpopper
>uw-imapd, spamassassin and vexira, but I wanto to switch to a more
>scalable architecture.
>I want to ask if you know of an ideal solution for this using free

One possibility (there are many variations):

Director: gatewaying ports 25, 80, and 143.
Port 25 Real Servers: sendmail+spamaassassin+clamav (configure procmail
for Maildir format)
Port 143 Real Servers: courier-imap
Port 80 Real Servers: apache+webmail_app

>[Slave 1]  [Sl 2]  Layer 1
>AntiSPAM and Antivirus Layer: This would filter SPAM with Spamassassin
>or DSPAM and Vexira.
>|Mail free of spam an virus, is redirected to real mail servers
>[Virtual Server]
>(load balances real servers, for them to receive filtered mail)

The problem is that the initial servers have to use the same userlists
as the second servers or else they blindly accept everything.  Bounces
should be generated at the SMTP level by the initial receiving machines,
keep that in mind.  LDAP is a scalable solution for this.

>My questions are:
>Is this the ideal solution?(in the context of free software)
>How would you redirect sendmail from layer 1 to layer 2?
>What MTA configuration would you recomend? Sendmail, Sendmail+Cyrus,

Postfix is also a good solution.  Qmail is terrific for throughput, but
if you want _any_ kind of features, you need to start patching it, at
which point, sendmail/postfix/exim gain the upper hand.  I prefer
sendmail or postfix myself as those are the two that I'm most familiar
Regards...              Todd
They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety.       --Benjamin Franklin
Linux kernel 2.6.3-8mdkenterprise   1 user,  load average: 0.11, 0.07, 0.02
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