You may have found this after installing the sendmail client, you get an error on the following boot as shown in the following pic
The cause of bug relates to the starting of network interfaces during the /etc/rc0.d/ phase of startup, and the contents of these files are responsible
These files re-configure sendmail on boot, supposedly only if there’s been changes that require the sendmail config to change, but in reality cause the error that was reported.
It happens because these files get called when filesystem is read-only, so the newly generated sendmail config files cannot be saved.
A tempory solution is to remove the 2 files refered to above.