Print Page | Close Window

specific sender not forwarded

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=5297
Printed Date: 01 November 2025 at 5:44pm


Topic: specific sender not forwarded
Posted By: smeyermann
Subject: specific sender not forwarded
Date Posted: 08 August 2005 at 12:02pm

I am having a problem with a particular sender not being able to send email to me. I have whitelisted the address but for some reason SPAMFilter is not forwarding the message to my internal email server. I am running the latest build 2.6.3.473. Below is what is happening in the log file

08/08/05 08:54:21:866 -- (3188) Disconnect
08/08/05 08:55:51:344 -- (1964) Connection from: 209.150.200.4  -  Originating country : United States
08/08/05 08:55:51:865 -- (1964) Resolving 209.150.200.4 - mp1.msp.eschelon.com
08/08/05 08:55:51:865 -- (1964) Bypassed all rules for: mailto:xxx@mydomain.com - xxx@mydomain.com from mailto:xxx@copytechprinting.com - xxx@copytechprinting.com ( Whitelisted EMail Address From)
08/08/05 08:56:52:091 -- (1964) Disconnect

Thanks.

 


Replies:
Posted By: LogSat
Date Posted: 08 August 2005 at 3:03pm
SpamFilter has an inactivity timeout of 60 seconds. If during that timeframe no packets are received from the remote server, SpamFilter will disconnect the sender.

From the log entries you included, it does seem as if the remote server is disconnected about 60 seconds after the last command (last command is at 8:55:51, the disconnect occurs at 6:56:52).

The good news is that this value can be changed (by modifying the ReadTimeout value in SpamFilter.ini file), the bad is that there may be a deeper problem.
 
We've run into the following scenario with some users:
The company had an antivirus/firewall in front of SpamFilter that intercepted emails before they reached SpamFilter. If a remote user either sent an email with a large attachment or had a slow connection, the firewall would hold/scan the email for a long time (> 60 seconds) before passing it onto SpamFilter. SpamFilter would thus disconnect the firewall before receiving the email. This issue was easily fixed by increasing the timout value.
 
Another issue I've seen was with the Internet Mail Connector in Exchange 5.5. We saw an install of Exchange 5.5 that had a bug in that it would not send the correct end-of-email sequence. All emails are terminated with the sequence (a dot on a standalone line):
<CR><LF>.<CR><LF>
 
in Hex characters this is $0D $0A $2E $0D $0A.
 
Exchange server would occasionally corrupt that sequence by replacing a 0D with a 00:
 
$0D $0A $2E $00 $0A
 
Since the end of email sequence was incorrect, SpamFilter (and other applications...) kept on waiting for the correct sequence, which Exchange never provided, and thus all sorts of problems were occurring. Unfortunately we do not know if the bug was ever fixed, as Exchange was upgraded to 2000 and the problem disappeared.

One more thing you may want to try is the "debug view" in SpamFilter. If you know the IP address of the sender's server, under the "Settings" and then "Debug View" you can try monitoring traffic from that IP. SpamFilter will catch the initial SMTP traffic, and some of the content. This will give you an idea of what is happening.



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

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

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


Print Page | Close Window