Information
The recommendation is to enable running sendmail in MTA mode to support local applications that require legacy MTA (i.e., connection via port 25) support.
Recall the preferred recommendation is to not run sendmail locally
.
Solution
Create a backup copy of /etc/mail/sendmail.cf :
cp -p /etc/mail/sendmail.cf /etc/mail/sendmail.cf.pre_cis
Edit:
vi /etc/mail/sendmail.cf
Replace: (assuming the default configuration)
O DaemonPortOptions=Name=MTA
with
O DaemonPortOptions=Name=MTA,Addr=localhost