sendmail.mc

Solution
To implement the solution, please execute the following steps:

1. Edit /etc/mail/sendmail.mc to have:

define(`SMART_HOST',`')

and

DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl



Do NOT edit /etc/mail/sendmail.cf as it may cause unexpected results.

(The "DAEMON_OPTIONS" line is a security measure - it allows sendmail to accept e-mail only from the local server. If you do not need otherwise, this is a good security practice. )

2. Regenerate sendmail.cf from sendmail.mc:

# m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf

3. Restart the sendmail service:

# service sendmail restart