The F= delivery agent equate is probably more fraught with peril than the others. The delivery agent flags specified with F= tell sendmail how the delivery agent will behave and what its needs will be. These delivery agent flags are used in one or more of three ways.

First, if a header definition relies conditionally on a delivery agent flag:

H?P?Return-Path: <$g >
  apply if P delivery agent flag is specified in F= delivery agent equate

and if that delivery agent flag is listed as a part of the F= delivery agent equate:

Mlocal, P=/bin/mail, F=rlsDFMmnP, S=10, R=20, A=mail -d $u
                               apply in header

that header is included in all mail messages that are sent via this delivery agent.

Second, if a delivery agent needs a special command-line argument that sendmail can produce for it but requires that argument only under special circumstances, selected F= delivery agent flags can produce that result. For example, the F=f delivery agent flag specifies that the delivery agent needs a -f command-line switch when it is forwarding network mail.

Third, the F= delivery agent flags also tell sendmail how this particular delivery agent behaves. For example, the F= delivery agent flag might specify that it perform final delivery or require that it preserve uppercase for usernames.

Many delivery agent flags have special meaning to sendmail; others are strictly user-defined. All the delivery agent flags are detailed at the end of this chapter (Section 20.8).

Note that whitespace characters ...

Get Sendmail, 3rd Edition now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.