Options can be set on the command line or in the configuration file. The -d37.1 (a.k.a. -d37) debugging switch allows you to watch each option being defined. As each is processed, this message is first printed, without a trailing newline:

setoption: name (char).sub =val  

Here, name is the option's multicharacter name, char is its single-character equivalent (or a hexadecimal value if it is non-ASCII), and sub is the subvalue for that option if there was one. Finally, val is the value being given to that option. If the option has already been set from the command line and is thus prohibited from being set in the configuration file, sendmail prints:

(ignored)

A newline is then printed, and the job is done. If defining the option is permitted, sendmail next checks to see whether it is safe (Section 24.2.4). If it is not, sendmail prints:

(unsafe)

If it is unsafe, sendmail checks to see whether it should relinquish its current privileges. If so, it prints:

(Resetting uid)

A newline is then printed, and the option has been defined.

The -d37.1 debugging switch also shows the modifier flags set for each DaemonPortOptions option. For example, consider the following:

setoption DaemonPortOptions (O)=Name=MTA
Daemon MTA flags:
setoption DaemonPortOptions (O)=Port=587, Name=MSA, M=E
Daemon MSA flags: NOETRN

The first setting of the DaemonPortOptions option sets no modifier flags so the line following it shows no flags. The second setting of the DaemonPortOptions option sets the M=E modifier flag. The line following it shows that that flag means to disallow ETRN. See DaemonPortOptions in Chapter 24 for the meaning of the various possible modifier-flags.