Mailer statistics logs
The sendmail command tracks the volume of mail being handled by each of the mailer programs that interface with it.
Those mailers are defined in the /etc/mail/sendmail.cf file.

To start the accumulation of mailer statistics, create the /etc/mail/statistics file by typing the following:
touch /etc/mail/statistics
If the sendmail command encounters errors when trying to record statistics information, the command writes a message through the syslog subroutine. These errors do not affect other operations of the sendmail command.
The sendmail command updates the information in the file each time it processes mail. The size of the file does not grow, but the numbers in the file do. They represent the mail volume since the time you created or reset the /etc/mail/statistics file.