Mailing List Message #6540
From: Peter Jones <>
Subject: Anti-Spam Problems
Date: Mon, 17 Jul 2000 14:03:07 -0700
To: <sims>
X-Mailer: Microsoft Outlook Express 5.00.2919.6600
Dear SIMSers:

I have installed SIMS in a small LAN to serve about 5-6 email accounts
in my wife's business. We are an all-Mac 10BaseT LAN (except for one
lone Wintel laptop which we inherited). We have a dedicated DSL link
with a single exposed static IP address; IPNetRouter (IPNR) providing
DHCP, router, and firewall services; and FTP, Web, and (now) mail
service behind the firewall.

Up until now, we've been using Earthlink for SMTP service and
for POP3 service. Putting in SIMS will allow us to drop the Earthlink
service, so there is some excitement there. Because we are serious
about preventing SPAM abuse, I enabled all 3 anti-spam options under
SMTP services as follows:

"Relay for Clients Only" is CHECKED. Under the "client hosts" window
we have "" (without quotes), representing the
internal LAN DHCP addresses. Currently the highest IP address in use
is The LAN side of the firewall is, so no
outgoing mail originates from that address. The mail/ftp/web server is, static.

"Verify Return Path" is CHECKED.

"Blacklist DNS Server" is CHECKED. We use <> based on
what I've learned from earlier discussions on this list. We have no IP
addresses loaded into the "Blacklisted IP addresses" window.

We are having difficulty sending email using SIMS. Currently the mail
client is Outlook Express 5.0. I've confirmed that the sending
workstation IP address is, but when I try to send mail I
get the "we do not relay" message. However, if I do a check mail,
followed immediately by a send mail, the mail goes. I'm assuming that
SIMS is allowing the work station to check mail (using password
authentication) and then a send mail command within 30 seconds goes

I only have one workstation implemented to use SIMS so far, so I have
not checked it against another machine. The other workstations are
still using Earthlink/

Frankly, everything was working right until I turned on the "Blacklist
DNS server" function and then it went bad. I can right it by turning
Blacklist DNS server off again, but I'm uncomfortable with this
solution...I don't want my server hijacked by spammers.

Does anyone have any ideas of additional things to try/tweak to
correct this situation?

Thanks in advance

Peter Jones
LMW Associates

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