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my today's morning message about reverse DNS

Printed From: LogSat Software
Category: Spam Filter ISP
Forum Name: Spam Filter ISP Support
Forum Description: General support for Spam Filter ISP
URL: https://www.logsat.com/spamfilter/forums/forum_posts.asp?TID=162
Printed Date: 03 November 2025 at 8:55pm


Topic: my today's morning message about reverse DNS
Posted By: Guests
Subject: my today's morning message about reverse DNS
Date Posted: 04 April 2003 at 7:55am

Roberto,

My today's message about dns test sugesstions is lost somehow... :((( It it possible to take it back?

Also, new forum is not working correctly under opera 7.03, 7.1b.... now have to use loose IE...


Replies:
Posted By: LogSat
Date Posted: 04 April 2003 at 11:49am
The Mozilla-based browsers whould work as well, even if with less features.
 
I was able to recover your post on the old forum below. I'll answer it in a reply to this post.
 
Roberto Franceschetti
LogSat Software
 
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There is an option to filter messages if remote IP does not have a reverse DNS record. (i think it tests current connection's ip address of remote server)

What about to test (make a dns lookup) IF senders domain have mx or A record or CNAME? Example: we have incoming connection from open relay openrelay.ru (10.10.10.10) is sends us 200 msgs from fake.net domain.

We're looking up if openrelay.ru have PTR, it have, ok, NOW we are making a dns lookup for mx record of fake.net... it's not exist so we reject this mail. OR may be another variant? we are cheking mx record of the first server in the chain.

Example:

When the mail sender identifies itself as john@mail.somewhere.com, we will cut down the domain part of the email address (mail.somewhere.com) and checks whether the DNS MX record (or DNS A or CNAME, depending on our settings) of mail.somewhere.com exists or not.

If it does not exist - block the mail immediately.

Posted By: LogSat
Date Posted: 04 April 2003 at 11:54am

This validation of the sender's domain was something we had in the back of our minds as well, but still did not have a chance to implement yet. We will be adding it soon though, thanks for the suggestion!

Roberto F.
LogSat Software


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