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SpamFilter don't close connection after quit

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Hassan View Drop Down
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    Posted: 13 January 2010 at 6:27pm
Thanks folks.

I'll explain the scenario to the other company who complain.
Worldsoft
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gillonba Quote  Post ReplyReply Direct Link To This Post Posted: 13 January 2010 at 6:20pm
Sometimes you will get complaints because a server does not respond to greylisting well.  We had a customer complain last week that they were not getting messages from one of their clients...   Turns out the mail server would only try sending once, and since the client was only sending one message every couple days they never ended up in the greylist cache.  We ended up adding them to our cache manually.

I even received a message a month ago in broken Engrish complaining that our spam filter was blocking messages from their, in his words, "spam appliance", and asking us to disable greylisting.  Needless to say, that message ended up in the circular file real quick
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LogSat Quote  Post ReplyReply Direct Link To This Post Posted: 13 January 2010 at 5:44pm
Hassan,

When SpamFilter rejects a connection due to the greylist filter, the remote IP address (McAfee in your case) will be forcefully disconnected. If the remote server (McAfee) does not recognize that the connection was closed before trying to send the "QUIT" command, that command will of course fail as there isn't a connection anymore.

Please note that the greylist filters are designed to reject all connections from an IP for a few minutes (5 by default). After that initial interval of time, if the IP retries to connect, the connection will always be allowed. More details on the greylist filter are found here:

This said, the complain of "not being able to send an email without restarting server" from the remote administrators may be just an issue of not knowing what greylisting is, and of the fact that by the time the admins restarted the mail server, that initial 5 minutes delay went by, and thus from then on the McAfee server was able to send emails (regardless of the reboot).
Roberto Franceschetti

LogSat Software

Spam Filter ISP
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Hassan View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hassan Quote  Post ReplyReply Direct Link To This Post Posted: 13 January 2010 at 5:43pm
Originally posted by gillonba gillonba wrote:

I'd have to agree.  Greylisting has been working well for us.  Are you running the latest version?

We are running the version 4.1.2.819
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hassan Quote  Post ReplyReply Direct Link To This Post Posted: 13 January 2010 at 5:41pm
Originally posted by Neolisk Neolisk wrote:

Disable McAfee? :)


This log is from the sender part.

We don't have McAfee. The sender complain against our Spamfilter that after sending QUIT connection is keeped open.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gillonba Quote  Post ReplyReply Direct Link To This Post Posted: 13 January 2010 at 5:24pm
I'd have to agree.  Greylisting has been working well for us.  Are you running the latest version?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Neolisk Quote  Post ReplyReply Direct Link To This Post Posted: 13 January 2010 at 4:09pm
Disable McAfee? :)
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Hassan View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hassan Quote  Post ReplyReply Direct Link To This Post Posted: 13 January 2010 at 8:30am
Hi,

We have some complains that if the greylisting is enabled the "QUIT" request don't close the connection. And the only way to be able to send an email to us is restarting the mail server

Quote
[McAfee]: test mail xxx.xxx.xxx.xxx test@sender.com test1@recipient.com
12212009 14:04:59:Reply: '220 incoming.spamfilter.recipient.com
Welcome to Recipient Incoming SMTP Server 2'
12212009 14:04:59:Sending: HELO mail02.sender.com
12212009 14:04:59:Reply: '421 This server implements greylisting, please
try again in 300 seconds'
Failed: e-mail transaction is incomplete. (421, 'This server implements
greylisting, please try again in 300 seconds')
12212009 14:04:59:Sending: QUIT
Failed: unable to close the transaction channel.
[McAfee]:


Any idea?






Edited by Hassan - 13 January 2010 at 9:05am
Worldsoft
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