Cannot log into server

Per following the guide (SMTP setup tutorial setup for name@yourdmain.com) which has since been removed, I cannot log into the server.

It is receiving  mail just fine.

Here is what I am seeing in the mail log (which is not very helpful at all)

How I am connecting it using Outlook  with the automatic set up.
On another computer, I have it already set up in Outlook, but it does not connect either


Feb 10 04:12:00 s1 postfix/smtpd[20356]: warning: 187.172.108.16: hostname dsl-187-172-108-16-dyn.prod-infinitum.com.mx verification failed: Name or service not known
Feb 10 04:12:00 s1 postfix/smtpd[20356]: connect from unknown[187.172.108.16]
Feb 10 04:12:00 s1 postfix/smtpd[20356]: setting up TLS connection from unknown[187.172.108.16]
Feb 10 04:12:00 s1 postfix/smtpd[20356]: Anonymous TLS connection established from unknown[187.172.108.16]: TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)
Feb 10 04:12:00 s1 postfix/smtpd[20356]: lost connection after STARTTLS from unknown[187.172.108.16]
Feb 10 04:12:00 s1 postfix/smtpd[20356]: disconnect from unknown[187.172.108.16]
Feb 10 04:12:00 s1 postfix/smtpd[20356]: warning: 187.172.108.16: hostname dsl-187-172-108-16-dyn.prod-infinitum.com.mx verification failed: Name or service not known
Feb 10 04:12:00 s1 postfix/smtpd[20356]: connect from unknown[187.172.108.16]
Feb 10 04:12:00 s1 postfix/smtpd[20356]: lost connection after EHLO from unknown[187.172.108.16]
Feb 10 04:12:00 s1 postfix/smtpd[20356]: disconnect from unknown[187.172.108.16]
[root@s1 ~]# tail /var/log/maillog
Feb 10 04:12:00 s1 postfix/smtpd[20356]: warning: 187.172.108.16: hostname dsl-187-172-108-16-dyn.prod-infinitum.com.mx verification failed: Name or service not known
Feb 10 04:12:00 s1 postfix/smtpd[20356]: connect from unknown[187.172.108.16]
Feb 10 04:12:00 s1 postfix/smtpd[20356]: setting up TLS connection from unknown[187.172.108.16]
Feb 10 04:12:00 s1 postfix/smtpd[20356]: Anonymous TLS connection established from unknown[187.172.108.16]: TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)
Feb 10 04:12:00 s1 postfix/smtpd[20356]: lost connection after STARTTLS from unknown[187.172.108.16]
Feb 10 04:12:00 s1 postfix/smtpd[20356]: disconnect from unknown[187.172.108.16]
Feb 10 04:12:00 s1 postfix/smtpd[20356]: warning: 187.172.108.16: hostname dsl-187-172-108-16-dyn.prod-infinitum.com.mx verification failed: Name or service not known
Feb 10 04:12:00 s1 postfix/smtpd[20356]: connect from unknown[187.172.108.16]
Feb 10 04:12:00 s1 postfix/smtpd[20356]: lost connection after EHLO from unknown[187.172.108.16]
Feb 10 04:12:00 s1 postfix/smtpd[20356]: disconnect from unknown[187.172.108.16]