[Dovecot] Sizing MTA servers

[Stan Hoeppner]

On 1/17/2014 12:36 PM, Sven Hartge wrote:
...
> http://www.exim.org/exim-html-current/doc/html/spec_html/ch-access_control_lists.html#SECTcontrols
> 
> ,----
> | control = cutthrough_delivery
> |
> | This option requests delivery be attempted while the item is being
> | received. It is usable in the RCPT ACL and valid only for
> | single-recipient mails forwarded from one SMTP connection to another. If
> | a recipient-verify callout connection is requested in the same ACL it is
> | held open and used for the data, otherwise one is made after the ACL
> | completes. Note that routers are used in verify mode.
> |
> | Should the ultimate destination system positively accept or reject the
> | mail, a corresponding indication is given to the source system and
> | nothing is queued. If there is a temporary error the item is queued for
> | later delivery in the usual fashion. If the item is successfully
> | delivered in cutthrough mode the log line is tagged with ">>" rather
> | than "=>" and appears before the acceptance "<=" line.
> |
> | Delivery in this mode avoids the generation of a bounce mail to a
> | (possibly faked) sender when the destination system is doing
> | content-scan based rejection.
> `----

The OP is obviously making accept/reject decisions at the gateway MTAs
using the usual SMTP connection and header analysis methods, and -then-
doing his SA scoring.  So this cutthrough mode simply won't work.  The
mail must be accepted and queued, piped to SA for analysis, re-queued,
then relayed to his mailbox servers.

-- 
Stan