Direct submission of email is accomplished by running sendmail on the command line:

% /usr/sbin/sendmail address 
% /usr/sbin/sendmail -t < file 
% /usr/sbin/sendmail -bs

The first form shows the recipient address being set as part of the command line. The second form shows the recipient address being parsed from the headers in the file. And the third form shows the recipient being taken from an SMTP session run via standard input and output.

Regardless of how you submit messages to sendmail, on the command line or with -bs, it is still considered direct submission. When a message is directly submitted it is of a different nature than a message received over a socket. When a message is directly submitted, the ${daemon_flags} sendmail macro (${daemon_flags}) is given one of two possible sets of values. If the -G command-line switch (-G), which specifies gateway submission mode, is specified, the values are CC f. If the -G command-line switch is omitted, the values are c u.

CC f

The CC means to not canonify hostnames. The f means to require that all hostname be supplied fully canonified.

c u

The c means to canonify all hostnames. The u means that hostnames do not need to be supplied in canonified form.

But note that with the mc configuration, the default for the submit.cf file is to define the DaemonPortOptions Modify= with the character E, which means to disallow use of the ETRN command.

If you wish to specify different flags, you can use this DirectSubmissionModifiers option, which is declared like this:

O DirectSubmissionModifiers=chars                  configuration file (V8.12 and later) 
-ODirectSubmissionModifiers=chars                  command line (V8.12 and later) 
define(`confDIRECT_SUBMISSION_MODIFIERS',`chars') mc configuration (V8.12 and later) 

Here, chars is of type string and consists of the characters that are used by the DaemonPortOptions option's Modifier= equate's flags (See this section). There is no need to double the uppercase flags because sendmail will do that automatically.

The chars you list become the flags used for direct submission and replace the default flags.

Note that you cannot use the DirectSubmissionModifiers option on the command line. If you do, it will be accepted but the default flags will continue to be used:

-ODirectSubmissionModifiers=chars         command line does not work 

The DirectSubmissionModifiers option is not safe. If specified from the command line, it can cause sendmail to relinquish its special privileges.