Hi,
Thanks for the responses. Now, I understand the NDR using From: <> is legitimate and should not be changed. In my mail server, i have enabled sender access using the following parameter. smtpd_recipient_restrictions = check_sender_access hash:/etc/postfix/sender_access, check_recipient_access hash:/etc/postfix/sender_access reject This was rejecting the mail with the 554 Recipient address rejected: Access denied Now, I have enabled null sender using <> in file /etc/postfix/sender_access, based on the information available in http://www.postfix.org/access.5.html ( refer Note: in section EMAIL ADDRESS PATTERNS ) After entering the captioned entry, the messages are accepted for delivery. Now, my concern is my mail server should not be an OPEN RELAY. I tried checking it on http://www.checkor.com/ Although, the results are negative, the site has the following disclaimer. * We do our best to check to see if you mailserver is an open relay. Even if your mail server tests negative on this site, it may still not be 100% secure Pls. suggest. Rgds, Santosh Malavade On Tue, Feb 28, 2012 at 5:38 PM, Wietse Venema <wie...@porcupine.org> wrote: > santosh malavade: > > Hi, > > > > > > I am trying to change the envelope sender appearing in Non Delivery > Reports > > as from=<> using sender_canonical_maps hash file > > According to Internet Mail Standards (RFC5321 etc.) non-delivery > reports must be sent with the null sender. > > Wietse > > RFC 5321 > 3.6.3. Message Submission Servers as Relays > > ... > > If an SMTP server has accepted the task of relaying the mail and > later finds that the destination is incorrect or that the mail cannot > be delivered for some other reason, then it MUST construct an > "undeliverable mail" notification message and send it to the > originator of the undeliverable mail (as indicated by the reverse- > path). Formats specified for non-delivery reports by other standards > (see, for example, RFC 3461 and RFC 3464) SHOULD be used if > possible. > > This notification message must be from the SMTP server at the relay > host or the host that first determines that delivery cannot be > accomplished. Of course, SMTP servers MUST NOT send notification > messages about problems transporting notification messages. One way > to prevent loops in error reporting is to specify a null reverse-path > in the MAIL command of a notification message. When such a message > is transmitted, the reverse-path MUST be set to null (see > Section 4.5.5 for additional discussion). A MAIL command with a null > reverse-path appears as follows: > > MAIL FROM:<> > >
