Sendmail™ logs its activity through syslog. You need to set your LogLevel to 9 or higher. Versions 8.10.x and 8.11.x of Sendmail™ are supported.
Example 9.6. Sendmail™ Log Sample
Oct 29 14:46:13 mailhost sendmail[19504]: alias database /etc/aliases \ rebuilt by root Oct 29 14:46:13 mailhost sendmail[19504]: /etc/aliases: 40 aliases, \ longest 10 bytes, 395 bytes total Oct 29 14:52:33 mailhost sendmail[19584]: alias database /etc/aliases \ rebuilt by root Oct 29 14:52:33 mailhost sendmail[19584]: /etc/aliases: 40 aliases, \ longest 10 bytes, 395 bytes total Oct 29 15:00:00 mailhost sendmail[19633]: f9U000Y19633: from=root, \ size=257, class=0, nrcpts=1, msgid=<john.doe.1@1.mail.example.com>, \ relay=john.doe.2@2.mail.example.com Oct 29 15:00:00 mailhost sendmail[19633]: f9U000Y19633: to=root, \ ctladdr=root (0/0), delay=00:00:00, xdelay=00:00:00, mailer=local, \ pri=30257, dsn=2.0.0, stat=Sent Oct 29 16:00:00 mailhost sendmail[19672]: f9U100619672: from=root, size=257, \ class=0, nrcpts=1, msgid=<john.doe.3@1.mail.example.com>, \ relay=john.doe.2@2.mail.example.com Oct 29 16:00:00 mailhost sendmail[19672]: f9U100619672: to=root, \ ctladdr=root (0/0), delay=00:00:00, xdelay=00:00:00, mailer=local, \ pri=30257, dsn=2.0.0, stat=Sent Oct 29 17:00:00 mailhost sendmail[19696]: f9U200V19696: from=root, \ size=257, class=0, nrcpts=1, msgid=<john.doe.4@1.mail.example.com>, \ relay=john.doe.2@2.mail.example.com Oct 29 17:00:00 mailhost sendmail[19696]: f9U200V19696: to=root, \ ctladdr=root (0/0), delay=00:00:00, xdelay=00:00:00, mailer=local, \ pri=30257, dsn=2.0.0, stat=Sent