Milter-greylist

8 \u0444\u0435\u0432\u0440\u0430\u043b\u044f 2016�\u0433. 5:23:51 CET, "Bob Friesenhahn bfriesen@... [milter-greylist]" <milter-greylist@yahoogroups.com> \u043f\u0438\u0448\u0435\u0442:
>The site http://mxtoolbox.com/ claims that my inbound mail is 
>particularly slow.  The specific test page is at 
>http://mxtoolbox.com/domain/www.simplesystems.org/.  The claim is that 
>it takes 8.5 seconds to deliver a mail to my domain and results are 
>consistent.
>
>Yesterday I switched from early 1994 SPARC hardware (still with lots 
>of memory so almost everything is in RAM) to modern 64-bit Intel 
>hardware with fast SSDs and a ton of RAM.  The test page for this site 
>says that the timing between the new and old hardware is almost 
>identical.
>
>I am using milter-greylist as the Milter.  Unless the test page is 
>faulty, the only part of the chain which could take any time is 
>milter-greylist since it does DNS queries.  However, I am not seeing 
>any indicated slowness in the logs.  Only every once in many emails do 
>I see a long SPF lookup (have seen 15 seconds before).
>
>Is this test page faulty or is there something in my mail delivery 
>chain (e.g. milter-greylist) which is adding time?
>
>Bob

Hi Bob, do you by chance have stuff like GreetingDelay or somesuch in sendmail and/or some of the milters, maybe newly introduced in yiur remade setup?

This is one way to add consistent delays - waiting for some time and then emitting an SMTP server banner and beginning to process incoming bits at this point. This approach helps rule out spambots which connect and spew their monologue rightnaway.

An effectively similar option might be tarpitting (may be even in milter-greylist), especially against yet-unacquainted hosts.

And DNS can lag too, yes :-)

On another hand, why does a consistent and relatively short delay bother you? Humans do not normally connect (on 25/tcp unauthenticated) to your smtp so likely won't notice the lag? And on 587/tcp you can require auth and do away with most milters and other protections.

Anyhow, with greylisting you incur a larger delay on transfer of messages (at least first ones before autowhiting), which is what gets some people annoyed.

Jim
--
Typos courtesy of K-9 Mail on my Samsung Android