sendmail, 4th Edition

-N

Specify DSN NOTIFY information V8.8 and later

The -N command-line switch causes sendmail to append the DSN NOTIFY command to the ESMTP RCPT command. For example:

RCPT To:<[e-mail]> NOTIFY=SUCCESS

Here, sendmail is requesting that the other site return notification of successful delivery.

The -N command-line switch also causes sendmail to behave as though it got the NOTIFY command when producing a local bounce message. That is, -N affects the other sites’ behavior on SMTP mail, and the local site’s behavior on local delivery.

Should the message be successfully delivered by a host that understands DSN, or by the local host, a return message will be sent to the sender. If either site is running V8.8 or later sendmail, that return message will look (in part) like this:

Date: Fri, 14 Dec 2007 08:11:43 −0800 (PST)
From: Mail Delivery Subsystem <MAILER-DAEMON>
Subject: Return receipt
Message-Id: <[e-mail]>
To: <[e-mail]>
MIME-Version: 1.0
Content-Type: multipart/report; report-type=delivery-status;
        boundary="f21IuJf8029510.834702270/other.site
Auto-Submitted: auto-generated (return-receipt)

This is a MIME-encapsulated message

--f21IuJf8029510.834702270/other.site

The original message was received at Fri, 14 Dec 2007 08:11:43 −0800 (PST)
from other.site [204.255.152.62]

   ----- The following addresses had successful delivery notifications -----
friend (successfully delivered to mailbox)

The -N command-line switch tells the NOTIFY command what to include ...