iis email issues

My expression build on iis server will not send emails. The communicate module gives me the following error.

An Error Was Encountered

Unable to send email at this time.

220 ICATMAIL1.ICAT.com Microsoft ESMTP MAIL Service ready at Wed, 17 Jun 2015 08:57:15 -0600

hello:

The following SMTP error was encountered:

Unable to send email using PHP SMTP. Your server might not be configured to send mail using this method.

My host (in this case the client) has tested email form the server outside of EE and the server does send email.

My EE email configuration is set to SMTP. The server doesn’t require username and password but EE won’t allow those fields to be empty.

Any suggestions?

Thank you.