Mailing List Message #105807
From: Bill Cole <>
Subject: Re: Unique entries for SMTP Prompt Delay
Date: Thu, 10 Sep 2015 22:43:38 -0400
To: CommuniGate Pro Discussions <>
X-Mailer: MailMate (1.9.2r5107)
On 10 Sep 2015, at 14:39, Tom Rymes wrote:

Today, however, I accidentally discovered that my currently configured prompt delay for SMTP (currently set to 23s) was to blame. While testing, I set the delay to 2s and suddenly a slew of e-mails showed up in my inbox.

Based on over a decade of using greeting delays with Sendmail, Postfix, and other tools that allow for measurement of just how fast offenders talk and how long impatient senders will wait, I'd say 2s is very close to the sweet spot for a greeting pause. The last time I did a careful analysis with varying times was years ago, but I've never seen in production or testing any negative impact of delays <5s and the vast majority of fast-talkers start in under a half-second because they are predominantly hyper-optimized sending bots. The legitimate(ish) senders who fast-talked before delays were common have all reformed their practices and the most impatient senders who once timed out too fast have mostly been spanked into compliance with the standard or at least something within an order of magnitude. It's a bit of a surprise that any sender worth caring about is still giving up in <23s, but I guess stupidity has a very long tail.

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