Mailing List Message #15199
From: Bill Cole <>
Subject: Re: Reasonable Connection Timeout
Date: Thu, 30 Mar 2006 20:09:58 -0500
To: SIMS Discussions <>
At 4:15 PM -0700 3/30/06, Warren Michelsen  imposed structure on a stream of electrons, yielding:
I'm having a problem with one company, a cable Internet provider, connecting to my mail server. They say it cannot be contacted, that connection attempts by their server to mine time out.

How quickly should a server time out while waiting for a response from my server? What's a reasonable amount of time? Should a server give up if there's no response within the first 10 seconds?

That's absurd, and in direct conflict with long-established norms as well as the guideline in RFC2821 of 5 minutes on initial connection. Many modern Sendmail systems will start with a configurable pause on connect to detect and police the connect+blast variety of spammer, and will stretch that pause in an orderly fashion under load as a way to back off the demands of clients without dropping them. Any mail sender timing out at 10 seconds is either staffed by idiots or is intentionally degrading their mail service. The latter may sound odd, but with a growing number of options in the mail market for end users, some connectivity providers (notably Verizon and SBC) are behaving as if they do not consider mail  to be a core service and do not want to be in the business of providing it. Just as AOL had little user complaint when they junked their poor Usenet service (after years of doing worse with it year over year...) it may be that the connectivity providers are really hoping that over time they can get to the point where their link customers who really give a damn about mail have all chosen alternative providers, and they can simply turn off the legacy mail system altogether. SBC is already moving that way by encouraging their users to all use the co-marketed Yahoo services.

Bill Cole                        

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