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Greylist Issue / Feature Update

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jerbo128 View Drop Down
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    Posted: 24 April 2008 at 9:45pm

Running .782 Enterprise MS SQL, 2 servers

To start with - I love Greylisting.  I think it works very well most of the time.  However.....

I have several domains that email our customers that just cannot seem to get the greylisting.  mchsi.com, centurytel.net are the worst.  Their retry intervals on their mail queues seems to be 4 hours +.  My customers are constantly complaining about the huge delay that this causes in receiving mail.  I have added mail servers for these domains to the greylist using a permanent date, but each domain uses multiple mail servers.  With mchsi.com - we had 12 mail servers in the list permanently before the complaints went away.  With centurytel.net, I have 22 entries right now, and am still getting complaints each day - meaning that there are more mail servers out there that I don't know about.

Nearest I can tell, each of these 2 domains tries each mx once, then waits at least 4 hours to try again.  Sometimes it is over 12 hours.  Good luck trying to get their admins to lessen the retry interval.
 
My greylisting settings:
Primary server
GreyListInterval=280
GreyListLimboHold=2
GreyListAllowedHold=4
 
Secondary Server
GreyListInterval=580
GreyListLimboHold=2
GreyListAllowedHold=4
 
So, what can we do?  Implementing the greylist into the SQL database might help.  Would allow multiple servers to share the list of good ips.
 
Anyone else having issues like this?
 
Idea's?
 
Jeremy
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LogSat Quote  Post ReplyReply Direct Link To This Post Posted: 28 April 2008 at 10:12pm
Jeremy,

As you're note receiving any feedback form other users, I'll step in with our comments. Is there a reson you changed the "GreyListLimboHold" and the "GreyListAllowedHold" values so dramatically from their defaults (see below in grey)?

The GreyListLimboHold value of 2 hours you have, means that any server that as a retry interval of over two hours will practically never be able to connect, as after two hours it will be removed from the GreyList "limbo" list that holds the IPs that have connected once, and are held pending their retries. If they are removed after 2 hours from this list, you will block anyone who has a longer retry interval. Many servers will have retry intervals ranging from 20 minutes to 4 hours, so we really would not recommend setting values below 4 hours for this parameter.

The GreyListAllowedHold value of 4 you have tels SpamFilter to remove any IP that passed the greylist test after only 4 days. After they have been removed, the IP will once more have to go thru the greylisting process, thus causing a slight delay during the initial email connections. I would not recommend setting this value to anything lower than 20-30 days to avoid causing too many delays.

Leaving the default values will help greatly in reducing the problems you described. For companies that have dozens of outgoing IP address, it may take several days for them all to appear in the greylist allowed list, but even then, delays should be minimal, as each IP will only need to retry once after (in your worse case) 4 hours.

;The number of hours for which an IP will be held in the GreyList limbo before being removed. If the IP does not make a second attempt to deliver email before this many hours after the initial attempt, it will be removed from the GreyList limbo, and it will have to repeat the process next time it connects.
GreyListLimboHold=12
 
;The number of days for which an IP that passed the GreyList limbo and has been allowed to connect will remain allowed to do so. After this many days from the initial contact, the GreyList process will have to be repeated.
GreyListAllowedHold=60
 

Roberto Franceschetti

LogSat Software

Spam Filter ISP
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