Mailing List Message #5683
From: Stefan Jeglinski <>
Subject: Re: 2 questions - blacklisting followup
Date: Thu, 30 Mar 2000 00:56:45 -0500
To: SIMS Discussions <>
Based on previous spams that I can't believe I misinterpreted, I blacklisted a PSI dialup block from which we had received a direct connection. PSI is our ISP, so they provide our mail backup. But near as I can tell, PSI removed or otherwise retired the dialup block, and assigned one of the IPs to a mailserver. And you guessed it - thinking that I was still blocking a dialup range, I instead began blacklisting a box occasionally used to try to deliver mail to us.

The range is Of course, it does not now return a dialup block.

Question one: is there a way to find out how an IP block -used- to be assigned? This is to prove to myself I'm not crazy. Do ISPs do this sort of thing (reassign entire blocks) often?

Second, a list mom/postmaster who first alerted me to the issue tracked me down via the customized error message SIMS sends back when we reject via the blacklist. After we resolved everything, he wrote me this:

"Now, any chance of your mail server returning RFC 1894-compliant DSNs?
If I hadn't been dealing w/ your DSNs by hand, I'd have never noticed

I'd like to answer him intelligently. I at least looked at 1894 and now know that DSN is Delivery Status Notification. Is he saying that if this was being handled in automated fashion on his end... well, what the hell -is- he saying anyway?

I am perusing 1894 but frankly, it is so detailed I figured I might get a quicker answer from the list. The message returned by SIMS (via the backup server) is currently:

host []:
591 Your host is in our Black List. No mail will be accepted. Refer to
<> for more information.

I know this is what the other postmaster received, as he quoted it. What's wrong with this? I can't tell from the rest of headers if our backup server at PSI returned an additional message which itself is not RFC compliant. Is this message not compliant somehow? Even though we can modify SIMS STR# resources, should we really not be doing this?

Stefan Jeglinski

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