I am currently using the excellent article "The Perfect Server - Fedora 7" to set up my Fedora 7 desktop as a server.
I am using exim as my MTA. Here is a test I just ran:
[root@HostBlade ~]# telnet localhost 25
Connected to localhost.
Escape character is '^]'.
220 HostBlade.example.com ESMTP Exim 4.66 Sat, 14 Jul 2007 18:51:28 +0100
250 HostBlade.example.com Hello localhost [127.0.0.1]
mail from: <email@example.com>
rcpt to: <firstname.lastname@example.org>
354 Enter message, ending with "." on a line by itself
Subject: a test mail
451 Temporary local problem - please try later
So I check Exim main.log:
[root@HostBlade ~]# tail -2 /var/log/exim/main.log
2007-07-14 18:53:42 1I9lnK-0004g9-Qd malware acl condition: clamd: unable to connect to UNIX socket /var/run/clamd.exim/clamd.sock (No such file or directory)
2007-07-14 18:53:42 1I9lnK-0004g9-Qd H=localhost (test) [127.0.0.1] F=<email@example.com> temporarily rejected after DATA
With regards to the "/var/run/clamd.exim/clamd.sock (No such file or directory)" part, if I actually create the file clamd.sock then the error changes to "unable to connect to UNIX socket /var/run/clamd.exim/clamd.sock (Permission denied)" and additonally the Clamd Log will state that "clamd.sock already exists, please remove it" - which is the reason I removed it to do the above test. I seem to be caught in some kind of paradox here, lol.
Additonally, I created a user called clamexim and set User clamexim in the clamd.conf file. Also, to overcome the permission denied with clamd.sock I CHOWNed it to clamexim.exim and I think the permissions where set to 711 so I have the following users in /etc/passwd
clamav:x:498:497:Clamav database update user:/var/lib/clamav:/sbin/nologin
clamexim:x:503:93:Clam Antivirus Scanner:/home/clamexim:/bin/bash
All help greatly appreciated.