Re: [Exim] unwanted mutiple emails

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Szerző: Matthew Byng-Maddick
Dátum:  
Címzett: exim-users
Tárgy: Re: [Exim] unwanted mutiple emails
On Fri, Nov 09, 2001 at 09:23:05AM -0500, Joseph Kezar wrote:
> another copy? Is that so? If the message is marked as "D" for that user
> it should skip them though. So I thought.


This is basically correct. And your analysis is wrong.

The SMTP protocol is lock-step (except by use of the PIPELINING extension),
and for the most part, knowledge that a timeout happened will cause you to
know that a message was either delivered or it was not. However, there is
one state for which this is not true.

>>> DATA

<<< 354 Send data followed by <CRLF>.<CRLF>
>>> From: ....
>>> To: ...
>>> Subject: ...
>>> Other-headers: ....
>>>
>>> body text
>>> .


At this point, the receiving end must attempt to spool or deliver the
message. It will then return
<<< 250 Accepted id=...

If the sender times this out, the message may well have been delivered, but
the receiver never gets a chance to tell it, so the sender *has* to assume
that it hasn't.

I can't remember offhand which variable this is in Exim, but I find the
default timeouts to be sensible and not to cause this to happen in general.

MBM

-- 
Matthew Byng-Maddick         <mbm@???>           http://colondot.net/