Adrian Zaugg <a...@ente.limmat.ch> wrote: > Am 17.01.14 10:53 schrieb Stan Hoeppner: >> On 1/16/2014 6:56 PM, Murray Trainer wrote:
>> MTA = disk. Always has always will. Disk throughput is always the >> critical factor for queue performance, and an MTA is little more than a >> queue. Which makes it surprising that so many people ignore disk when >> talking about mail servers, as you have done here. > Exim tries to deliver every message without queueing it first. The documentation says something different: http://www.exim.org/exim-html-current/doc/html/spec_html/ch-how_exim_receives_and_delivers_mail.html ,----[ 6. Handling an incoming message | When Exim accepts a message, it writes two files in its spool directory. | The first contains the envelope information, the current status of the | message, and the header lines, and the second contains the body of the | message. The names of the two spool files consist of the message id, | followed by -H for the file containing the envelope and header, and -D | for the data file. `---- and ,----[ 7. Life of a message | A message remains in the spool directory until it is completely | delivered to its recipients or to an error address, or until it is | deleted by an administrator or by the user who originally created it. In | cases when delivery cannot proceed – for example, when a message can | neither be delivered to its recipients nor returned to its sender, the | message is marked “frozen” on the spool, and no more deliveries are | attempted. `---- So exim4 _always_ writes a message to disk first and _then_ tries to deliver the mail. But: there is a new delivery mode available since Exim 4.82, named "cutthrough delivery", set via as a control item in the RCPT ACL: 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. `---- Grüße, Sven. -- Sigmentation fault. Core dumped.