34.2.1 Pre-V8.7 Configuration-File Declarations

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 is different from x). Depending on the option selected, an argument may be required. There must be no intervening space between the single-character option name and its argument.

34.2.2 V8.7 Configuration File Declarations

Beginning with version 8.7, option names may 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)

Whenever the 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 all produce the same effect:

O QueueDirectory=/var/tmp
O queuedirectory=/var/tmp
O QuEuEdIrEcToRy=/var/tmp

There may be optional space (not tab) characters surrounding the = character:

O QueueDirectory = /var/tmp
                 
                spaces, not tabs

Multicharacter names in the configuration file must not be abbreviated or expressed in shorthand:

O QueueDirectory=/var/spool/mqueue     good
O QueueDir=/var/spool/mqueue           bad

Failure to use the full multicharacter name will cause sendmail to print spurious warnings every time it is run. The possible warnings are listed in Section 34.1.2.1, "Multicharacter name shorthand". Multicharacter names are beneficial because they allow option names to have mnemonic recognition. For example, the multicharacter name ForwardPath, which lists the default path for ~/.forward files, is much more recognizable than the single-character name J.