Re: [exim] Retry hint left over after successful delivery

Martin A. Brooks wrote:
> On Tue, June 1, 2010 06:08, W B Hacker wrote:
>>> 2. Once the mail has gotten into their system, whether that is delayed
>>> or
>>> not, it can take up to 2 hours or so for it to show up in mailboxes.
>>>
>> Now THAT is a scandal....
>
> Not really, SMTP makes no guarantee about how long message delivery will
> take. If you're relying on your messages reaching the destination inside
> a given time window, then SMTP is the wrong protocol to use.
>
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>

Welll. International Private Leased networks, as at the time I retired in 1994,
were held to a downtime of around two seconds a year.

In theory, neither terrestrial voice telephony nor smtp are even close to a
match for those data circuits - let alone GSM and friends.

In practice, however, smtp punches well above its weight 'often enough' - just
as voice telephony does - as to sustain a user-community *expectation* of
near-instantaneous delivery, and near-as-dammit all the time.

It is that statistically-supported and experience-driven expectation we have to
deliver to. RFC's tell us how. But not always 'how well'.

I'd bet the user community waiting out those two-hour transfers includes an
ever-increasing number who have acquired Gmail, MSN/Hotmail, Yahoo et al
accounts - first for 'emergency' workarounds, later for more and more traffic
just on the convenience factor.

Eventually, the involvement of the 'official provider' migrates from precarious
to historical.

End-users are merciless. And they care less about disclaimers than fish do about
bicycles.

YMMV


Bill