What is true regarding the command sendmail?

The `sendmail` command is used to submit mail or administer the queue, not typically run periodically by cron to deliver mail; MTAs handle delivery automatically or by internal queue runners.

Due to the historical prevalence of the Sendmail MTA, other MTAs like Postfix and Exim provide a `sendmail` compatibility layer. This means they install a `sendmail` executable (often a symlink or wrapper) that mimics the original Sendmail interface, allowing applications to submit mail without knowing the specific MTA in use.

The `sendmail` command itself does not print the MTA's queue history of sent mails. Commands like `mailq` or MTA-specific logs are used to inspect the mail queue or delivery history.

This is incorrect because many MTAs provide a `sendmail` compatible executable even if the original Sendmail MTA is not installed, for compatibility reasons.