Re: [exim] Cutthrough routing

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Author: Jeremy Harris
To: exim-users
Subject: Re: [exim] Cutthrough routing
On 2012-01-21 16:34, Jeremy Harris wrote:
> As the bug ( I've logged says:
>> The modern world of spammers faking envelope-from combined with antispam
>> defences doing content-scanning, combined with 2MX service provided by
>> separately maintained systems, results in a bounce problem.

I've updated the second patch. This fixes three issues:

1)  Headers were being sent onward with only a newline as a line-separator.
      A destination Exim system didn't care, but VPOP3 did.

2) If cutthrough-routing was requested for an item which turned out to have
     local delivery then immediate delivery was not done; the item was queued
     until the next queue-run.

3) Cutthrough was not working for (single) addresses resulting from a routing

More quirks noted:

    To take advantage of a recipient-verify connection, the use-sender option must
be used.  Also, unless no_cache is used a successful verification (up to the RCPT TO
phase) using the connection will be cached.  A subsequent connection for a later
message will then be avoided; the connection used for cutthrough being made after
the rcpt ACL.   This is operational but incurs the cost of routing the (second)
message twice, which is suboptimal.   Admittedly this is no worse than the traditional
case, routing once for the verify and once for the delivery.