-bD

Run as a daemon, but do not fork so that sendmail always runs in the foreground.

-bH

Purge persistent host status. 

-bh

Print persistent host status. 

-M

Assign a macro value. 

-N

Append the DSN NOTIFY command to the ESMTP RCPT command.

-O

Use to set a multicharacter configuration option. 

-p

Set the protocol and hostname. 

-R

Include the DSN RET command to the ESMTP MAIL command.

-U

Used to indicate that this is the very first step in this submission. 

-V

Specify the envelope indentifier for outgoing messages.