Beginning with V8.7 sendmail, configuration file options can use multicharacter option names. Prior to V8.7, only single characters were allowed. We describe the old form first, then the new.
The old form for an option command in the sendmail.cf file is:
OXargument← prior to V8.7
Like all configuration commands, the uppercase letter
O must begin the line. It is immediately followed
(with no intervening space) by another single letter, which selects a
specific option. Uppercase letters are distinct from lowercase for
single-character option names (that is,
x). Depending on the option
argument might be required.
There must be no intervening space between the single-character
option name and its argument.
Single-character option names should be considered deprecated in favor of the more modern multicharacter option names.
Beginning with V8.7, option names can be single-character or multicharacter. A space is used to differentiate between single-character and multicharacter (long) names:
O LongName=argument ← beginning with V8.7 ↑a space (not a tab)
O configuration command is followed
by a space (not a tab), everything following that space is taken as
the declaration of a multicharacter option. Unlike single-letter
option names, multicharacter names are interpreted by
sendmail without regard to case. Therefore, the following three examples ...