unable to connect to the SMPT server - CSharpcoder

I have a sharepoint site that sends out emails when a new task is added.
Currently when the site is trying to send out an email its never sent and
there is an error in the event viewer that read. [  Cannot resolve name of
SMTP host ] and instead of the server name its boxes. Now, the server itself
is able to connect to the smtp server and send email. (I created a tester C#
asp.net page) and I am getting those emails but not the ones sharepoint
should be sending out.

The SMTP server is configured for the outgoing email section. What could be
causing this issue?