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Whitelist available for GreyList filter

Printed From: LogSat Software
Category: Spam Filter ISP
Forum Name: Spam Filter ISP Support
Forum Description: General support for Spam Filter ISP
URL: http://www.logsat.com/spamfilter/forums/forum_posts.asp?TID=6985
Printed Date: 18 November 2017 at 10:59am


Topic: Whitelist available for GreyList filter
Posted By: LogSat
Subject: Whitelist available for GreyList filter
Date Posted: 10 October 2011 at 8:45pm
The greylist filter is a great tool that can be used to fight spam, as long as SMTP server follow the RFC guidelines. Per RFC, if an SMTP server is unable to deliver an email because the receiving SMTP server rejects the connection attempt with a 4xx error code (which indicates a temporary unavailability), they are supposed to retry the delivery after a few minutes.

Unfortunately some providers, notoriously Yahoo, do not respect the RFC. Instead of having the sending SMTP server retry after a few minutes, they delegate the delivery to another of their outbound SMTP servers on a different subnet. As this new SMTP server will be making its initial connection for the very first time, it will be rejected by the greylist filter. The provider will again not follow RFC requirements, and will pass on for delivery the email to yet another SMTP server. The story then repeats itself continuously, causing huge delays in the delivery of the email, until the email is eventually delivered by an SMTP server that was used in the past (which allows it to pass the greylist filter).

To try avoiding this issue, we are now generating every day a huge whitelist of about 125,000 known trusted IPs. To account for little-used SMTP servers on the same subnets, and to reduce the overall file size, we combined them into about 37,000 class-Cs.

The latest file is available at:
http://www.logsat.com/SpamFilter/pub/GreyListAllowed.txt" rel="nofollow - http://www.logsat.com/SpamFilter/pub/GreyListAllowed.txt

to install, you will need to stop SpamFilter, add (not replace) the entries from the above file to your existing \SpamFilter\Domains\GreyListAllowed.txt file, and then restart SpamFilter.
Do not worry about adding duplicates - SpamFilter will automatically parse that file upon startup, and remove any duplicates for you.


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Roberto Franceschetti

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

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



Replies:
Posted By: danego
Date Posted: 11 October 2011 at 6:31pm
Hi,
 
I downloaded the wget command for windows from here

http://users.ugent.be/~bpuype/wget/ - http://users.ugent.be/~bpuype/wget/

and I created a little 4 line batchfile and set it to schedule every week:
 
updategreylist.bat

wget http://www.logsat.com/SpamFilter/pub/GreyListAllowed.txt - http://www.logsat.com/SpamFilter/pub/GreyListAllowed.txt -O d:\spamfilter\UPDATES\dailygreylistallowed.txt [nextline]
net stop spamfilter [nextline]
type d:\spamfilter\UPDATES\dailygreylistallowed.txt >> d:\SpamFilter\Domains\GreyListAllowed.txt [nextline]
net start spamfilter [nextline]
I created a directory 'updates' in my logsat spamfilter folder to hold the downloaded file.
During the wget I change the name so that I don't get confused which is which.
Batch file is very simple
1 download file
2 stop spamfilter service
3 add downloaded file to existing greylist
4 start spamfilter service


Posted By: Wayne
Date Posted: 12 October 2011 at 9:49am

Great news! Thanx Roberto and danego for the nice batchfile!




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SF4.5.0.1-beta



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