DeliverByMin

Set default DELIVERBY interval V8.12 and later

RFC2852 defines a way to ensure that a message is delivered or bounced within a defined maximum window of time. This method is known as the DELIVERBY SMTP extension and is used like the following (shown in bold):

220 your.host.domain ESMTP Sendmail 8.12.7/8.12.7; Fri, 13 Dec 2002 10:09:06 −0600
(MDT)
EHLO another.host.domain
250-your.host.domain Hello another.host.domain [123.45.67.8], pleased to meet you
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-8BITMIME
250-SIZE
250-DSN
250-ETRN
250-DELIVERBY                                       ← note
250 HELP
MAIL From:<bob@another.host.domain> BY=600;R        ← note
250 2.1.0 <bob@another.host.domain>... Sender ok

Here, your site tells the connecting site that it supports the DELIVERBY SMTP extension by displaying the 250-DELIVERBY line. Then the other site recognizes that support and says that it wants the message delivered within 600 seconds by including the BY=600;R as part of the envelope sender MAIL From: command.

The ;R tells your server to not relay this message to a site that does not support this extension. The only possibility, other than ;R, is a ;N, which means the message can be relayed to another site, regardless of whether that other site supports this extension.

It is possible to run software or a configuration at your site in such a way that mail cannot be immediately delivered. If you screen all messages for viruses, for example, or if you queue all inbound mail and deliver from the queue, you will likely not be ...

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