Talk:Greylisting
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The article mentions storing triplets but doesn't say what this data is used for. Could someone add this?
Nate 19:25, 12 Jan 2005 (UTC)
[edit] North American spelling
The article says "the word is spelled 'graylisting' in North America", but I'm not sure this is true. Most of the U.S. sources I've seen use "greylisting", as the article does. Google reports 234,000 hits for "greylisting" vs. 9,340 for "graylisting" -- compare this to 56 million for "grey" vs. 114 million for "gray".
Do we have a source for the "North American spelling" claim? If not, I'd like to remove it. --67.188.121.29 09:37, 29 September 2005 (UTC) gfgd
- I concur, I'm active on several mailing lists frequented by Americans and have never seen it called "graylisting" (except maybe by novice admins who don't know any better). Zerbey 17:56, 14 November 2005 (UTC)
[edit] A few suggestions...
The comments about losing legitimate mail should really be changed to stress how rare losing legitimate mail is and how it is incorrect (according to the RFCs) for a mailer to fail to retry. I'm afraid some people may be scared off from trying this wonderful anti-spam technique for fear of losing mail, when losing legitimate mail really should not be a concern.
To respond to the earlier comment, the triplet stored is used to make the decision to allow the mail when the retry happens.
In response to the "arms race" disadvantage, there are others who would argue that spammer tools changing to circumvent greylisting is unlikely for several reasons. One is that spam tools have to frequently change the addresses used in their mails to avoid more basic blocking. The other is that spammers deal with such a high volume of mail, retrying messages isn't feasible.
In the Advantages section, it may be be wise to emphasize that the delay only applies the first time a new sender appears. Some greylist software times out entries after a specified period of time, to keep the database size from growing too large, so for example of if the timeout is set to 1 week and you have mail that regularly arrives once a month, it will be delayed every time. In that case, the delay shouldn't be too important. Local customization and white-listing is common.
As far as spelling, at least on implementation is called "Graymilter".
24.163.80.4 23:07, 22 January 2006 (UTC) Steve
- While you are absolutely correct in saying that "losing legitimate mail should not be a concern", the fact is that it is a concern and does happen. I ran greylisting for many months and became frustrated when a discovered I was losing legitimate mail. One case I remember was mail from a web site with home-grown order form software that did not follow standards. It never retried; I never got my mail. Another case was a web site where signup involved sending a confirmation code via email with instructions to click on the included link within five minutes. I had to make a specific exception to receive that mail within the time alloted. Users without control over their site's greylisting filter would have had much more difficulty. --Ghewgill 01:05, 23 January 2006 (UTC)
I don't understand. user:65.27.132.51
It should be noted greylisting is incompatible with sender verification which is standard on many mailservers now. A greylisted server will not be able to send mail to any recipient that has sender verification enabled. The sender verification will send a 450 response (as the sending server has refused to verify that it is a legitimate address) and the many (most? all?) greylisting systems just drop that response on the floor and never try again. 146.87.6.75 —Preceding comment was added at 14:18, 23 October 2007 (UTC)
[edit] Retry timing per RFC
The article mentions an RFC which "requires" 4 hour retries. What RFC is that? —Preceding unsigned comment added by 198.145.222.48 (talk • contribs) 19:57, 3 May 2006
- This is an excellent point. While many MTAs employ a strategy that attempts to re-transmit every 4 hours (as I recall), that is usually after the initial attempts to re-transmit at a higher frequency as laid out in RFC 2821:
- Experience suggests that failures are typically transient (the target system or its connection has crashed), favoring a policy of two connection attempts in the first hour the message is in the queue, and then backing off to one every two or three hours. [1]
- Of course, this is only an advisory, and not a requirement of the RFC, but unless someone can demonstrate an RFC that says otherwise, I think this article needs to be altered to reflect what the RFCs actually say. -Harmil 01:32, 4 May 2006 (UTC)
The 4 hour thing comes from the default configuration for some of the major unix mail servers and is a norm but not a standard
http://www.ietf.org/rfc/rfc2821.txt From: 4.5.3.2 Timeouts
"Initial 220 Message: 5 minutes - Many SMTP servers accept a TCP connection but delay delivery of the 220 message until their system load permits more mail to be processed."
Every greylist server I have will wait for 5mins before permitting valid retry. ViktorVaughn 15:50, 26 July 2006 (UTC)
