The mailstats utility displays the current mail statistics.
with a "C" lists the number of TCP connections.
specified in the sendmail configuration file.
-p      Output information in program-readable mode and clear statistics.
-o      Don't display the name of the mailer in the output.
/etc/mail/sendmail.cf   The default sendmail "cf" file.
/var/log/sendmail.st    The default sendmail statistics file.
The mailstats utility exits 0 on success, and >0 if an error occurs.