Mailing List CGatePro@mail.stalker.com Message #92359
From: Jeff Wark <jwark@tbaytel.net>
Subject: Re: Feature request: temporary greylist
Date: Tue, 28 Aug 2007 11:58:02 -0400
To: CommuniGate Pro Discussions <CGatePro@mail.stalker.com>
X-Mailer: CommuniGate Pro WebUser v5.0.13
Like you said, replies are important.

On incoming mail, unexpected triples need to be remembered, but maybe you need to expect certain 'doubles' of to/from + any IP address.  Almost like routing packets through firewalls.

Interesting.

On Tue, 28 Aug 2007 11:28:51 -0400
 Nicolas Hatier <nicolas.hatier@niversoft.com> wrote:
Also, the server should remember and perhaps guess a triple for the messages you send. When you send a message to someone, you don't want his reply to be delayed by one or a few hours. Since the IP to which the message is sent is not always the IP from which the message is received, well, there is often problems making that guess.

Also, messages from a single email address can be received legitimately from different IP, sometimes 10 or more. Just think of an email received from a @hotmail address. Even if one triple is listed, another message from the same sender would still be delayed.

I'm not sure greylisting is worth the delays. Users are expecting e-mail to be near instantaneous. Whether they should or not is out of the question.

Nicolas

Jeff Wark wrote:
Reading Wikipedia [http://en.wikipedia.org/wiki/Greylisting] I see that the one problem with greylisting is the requirement that the triples be remembered for a configurable period, perhaps a very long time [I was under the impression that they would just timeout and be forgotten again after the message was sent..should have thought it through].

On Tue, 28 Aug 2007 10:39:09 -0400
 Jeff Wark <jwark@tbaytel.net> wrote:
How does someone get on the greylist?

My understanding of greylisting was that if the to/from/ip triple had not been seen before, there would be a delay of a few hours.

So, with that [perhaps incorrect] understanding your features might be:

1) CLI functions to Add, Remove, and enumerate
Add would pre-add a triple to the list, pre-allowing it to send email without delay or a reduced delay
Remove would remove a triple from the list, making it unknown to the server and therefore forcing it to wait the whole delay period
enumerate - same.

2) If an IP doesn't exist in the temp greylist OR it does exist in the temp greylist but has not been delayed enough, issue a 4xx rejection.

3) Provide a method of time-expiring the greylist entries....same as before.

Again, this is based on my assumption of what greylisting is.

On Tue, 28 Aug 2007 07:01:01 -0700
 "Bret Miller" <bret.miller@wcg.org> wrote:
I think this has been requested before, but I'm going to do it again. Grey listing is being done more often, even by big servers like Yahoo and MSN/Hotmail as a method of reducing spam. Essentially the theory goes like this: we received spam from you, so we are now going to delay your email for a certain length of time. For many spammers, this is enough for them to give up delivering the spam.

I think this would be an easy feature to add to CGPro because it essentially already exists. The temporary blacklist works pretty much like a greylist would except it uses a 5xx rejection code instead of a 4xx code.

Here's how this feature would work in CGPro:

1. Provide CLI functions to add, remove, and enumerate the temporary greylist.

2. If an IP exists on the temp greylist, issue a 4xx rejection for the message before the data phase.

3. Provide a method of time-expiring the greylist entries, and settings that control the length of time IPs remain on the list.

4. (Optional) provide a rule action to "Add to greylist" so that admins could add IPs to the greylist based on results from external helpers.

Thanks,
Bret




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-- *Nicolas Hatier* <mailto:nicolas.hatier@niversoft.com>
/Niversoft idées logicielles/
/http://www.niversoft.com/



Jeff Wark
TBayTel Internet
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