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rdns bockking local ip?

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=5123
Printed Date: 03 June 2025 at 1:47am


Topic: rdns bockking local ip?
Posted By: erwinyu
Subject: rdns bockking local ip?
Date Posted: 02 April 2005 at 4:53pm

Correct me if I am wrong, does the Spamfilter check sender's Local IP and SMTP server's IP to see if it has Rdns setup?

Currently, I have user getting their email rejected because their Local IP doesn't have rdns, but the smtp server has rdns.

Is there a way to only check smtp server's rdns?

 

Thanks,

 

Erwin


Replies:
Posted By: Desperado
Date Posted: 02 April 2005 at 10:30pm

Erwin,

Please define "Local" user.  Normally, SpamFilterISP is not used for the "Client" to mail through (allthough it can be set up that way).

Having said that, If SpamFilter is configured to check for RDNS (a setting that is in the GUI) then the IP that connects to the SpamFilter Server must have a RDNS entry in the DNS server that is authoratative for that IP.

There are many tools to check for RDNS but the simplest is to run nslookup from a command prompt.  At the nslookup prompt type in the following command:

set type=ptr

Then if you type in the IP address in question, you can see the RDNS setting (if it exists).

A typical session would look like the following:

Microsoft Windows 2000 [Version 5.00.2195]
(C) Copyright 1985-2000 Microsoft Corp.

C:\Documents and Settings\das52>nslookup
Default Server:  ns1.mags.net
Address:  66.181.192.10

> set type=ptr
> 66.181.197.33
Server:  ns1.mags.net
Address:  66.181.192.10

33.197.181.66.in-addr.arpa      name = bg1-33.adsl.mags.net

Regards,

 



-------------
The Desperado
Dan Seligmann.
Work: http://www.mags.net
Personal: http://www.desperado.com

Posted By: Guests
Date Posted: 03 April 2005 at 3:58am

Dan,

Our client is not using spamfilter to mail through.  What happen is someone sends a email to our server.  So out spamfilter picks up the sender's local ISP IP and SMTP server IP.  Somehow, spamfilter is checking both IP to make sure it has rdns setup.

Does that sound like smth that spamfilter will doing?

I thought spamfilter only check for the server who tries to make connection to it.

Posted By: Desperado
Date Posted: 03 April 2005 at 4:08am

SpamFilter should only see, and test for RDNS on the IP that actually makes the connection to it.  Can you post a log entry?

Dan



-------------
The Desperado
Dan Seligmann.
Work: http://www.mags.net
Personal: http://www.desperado.com

Posted By: LogSat
Date Posted: 03 April 2005 at 10:43am
Erwin,

SpamFilter only performs IP-based checks on the IP that is making the connection to SpamFilter. Any other IPs that are listed in the email headers are ignored.

Depending on how the remote user sends the email, he can either connect with his PC directly to SpamFilter or it will be his mail server that will make the connection. It cannot be both, and SpamFilter will only check the IP making the connection.

Should you see two checks the only way that can happen is that the remote client is sending *two* emails, one going directly to SpamFilter, the other going thru his SMTp server. In this case, in the SpamFilter's logs you'll see multiple connections arriving, not one.


-------------
Roberto Franceschetti

http://www.logsat.com" rel="nofollow - LogSat Software

http://www.logsat.com/sfi-spam-filter.asp" rel="nofollow - Spam Filter ISP


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