DOKK / manpages / debian 11 / nullmailer / sendmail.1.en
sendmail(1) General Commands Manual sendmail(1)

sendmail - sendmail emulator interface for nullmailer

sendmail [ flags ] [ recipients ] < message

This program is a front end program for nullmailer-inject and nullmailer-smtpd. It is used by programs that expect a sendmail interface for sending email. After parsing the command-line arguments, this program executes either nullmailer-inject or nullmailer-smtpd depending on the presence of the -bs option on the command-line. See the documentation for nullmailer-inject for details on how messages are reformatted and queued.

Ignored for compatibility
Read mail from standard input (default).
List information about mail queue. This executes mailq.
Use the SMTP protocol on standard input and standard output. This executes nullmailer-smtpd.
Sets the full name of the sender.
Sets the envelope sender address.
An alternate and obsolete form of the -f flag.
Read message for recipients and ignore the command-line arguments.

mailq(1), nullmailer-inject(1), nullmailer-smtpd(1)