The -R command-line
switch tells sendmail to include the DSN RET
command with an ESMTP MAIL command:
MAIL From:<email@example.com> RET=full
MAIL From:<firstname.lastname@example.org> RET=hdrs
The RET command requests the receiving site to (or not to) include a
copy of the original message body in the bounced mail notification.
RET=full requests that both headers and the
message body be returned. RET=hdrs requests that
only headers be returned. The RET= command affects the receiving site
only if it agrees to handle the DSN extension to ESMTP. In the
absence of RET or remote DSN support, the receiving site is free to
return the message body if it so desires.
For local mail, sendmail uses this
-R command-line switch to determine how it will
handle local bounces. Normally, sendmail
includes everything (full) in a locally generated
bounce. By using hdrs you can restrict local
bounces to only the header portions of the original message.
The RET, and hence this -R command-line switch, is
useful in two circumstances:
For users sending email, this should be set to
full so that any bounced mail will include the
original message body. This helps to reduce the need for users to
archive their outgoing mail.
For mailing-list mailings or other batched broadcast messages, this
should be set to hdrs so that only the header
portion of the bounced message will be returned.
The form of the -R command-line switch looks like
Space between the -R and its argument is optional.
The arg must be present and must be either
hdrs (return only headers) or
full (return the body too). If it is any other
value, the following error is printed and the setting defaults to
Invalid -R value
The -R command-line switch can appear only once in
the command line. If it appears multiple times, the second and
subsequent appearances will result in this error message:
Duplicate -R flag
Beginning with V8.10, sendmail allows you to set
a policy of not returning the body, regardless of what is requested
by the sending site. You do this by setting the
PrivacyOptions=nobodyreturn option (See this section).