North American Network Operators Group|
Date Prev | Date Next |
Date Index |
Thread Index |
Author Index |
Re: Yahoo Mail problems ? (queue issues in general)
- From: Valdis.Kletnieks
- Date: Wed May 05 13:29:25 2004
On Wed, 05 May 2004 10:59:55 EDT, Mike Tancsa <email@example.com> said:
> Anyone else seeing Yahoo mail queue up today ? Some of their servers
> respond in about 10secs with the HELO banner, most others take more than
> 2m. Because of the recent increase in SPAM, I was looking to reduce the
> wait time for the initial HELO to 2m from 5m. However, the RFC calls for 5m
> on the HELO and another 5m for the MAIL command.
Do you have a handle on whether the delay is between the first SYN packet and
finally completing the 3-packet handshake, or is it between that and when the
220 banner actually arrives? Or are both phases an issue?
> Having a process block like that for up to 10m seems a bit excessive to
> deliver one email (and its probably a bounce to boot!). What are others
> doing? This problem seems to becoming more and more acute.
What I do is the *first* attemt to deliver the mail has a highly-non-compliant
5 second timeout (which is just enough for an initial SYN, 2 retransmits, and a
few hundred ms budget for RTT for a SYN+ACK) for the 3-packet handshake, and
then subsequent retries in the background are given a longer 5-min timeout. (I
gathered some stats for quite sime time before deploying that - out of several
million connection attempts, I found less than a dozen that took over 5 seconds
that did in fact complete in under 5 minutes). Once the 3-packet handshake
succeeds, they then get a 5 minute timeout to get the 220 banner out. Probably
not perfect, but it's close enough to keep the queues manageable...
Also, YMMV, so gather your own stats....
Description: PGP signature