Postfix sendmail command-line interface

Postfix has two Sendmail-compatible command-line options for DSN support.

• The first option specifies what notifications are sent for mail that is submitted via the Postfix sendmail(1) command line:

  $ sendmail -N success,delay,failure ... (one or more of these)
  $ sendmail -N never ...                 (or just this by itself)
  

  The built-in default corresponds with "delay,failure".

• The second option specifies an envelope ID which is reported in delivery status notifications for mail that is submitted via the Postfix sendmail(1) command line:

  $ sendmail -V envelope-id ...
  

  Note: this conflicts with VERP support in older Postfix versions, as discussed in the next section.