C# mailer - 550 Access denied - Invalid HELO name

Question

I know there are various thread out there related to this problem but i was unable to take any of the responses on those thread and make it work on my server.

So let try

Answer 1

Based on BEN answer I realized that I was missing the PRIMARY DND SUFFIX.

Mainly in order to find out your FQDN, you need to simply: 1) Open a Command Prompt 2) Type "ipconfig /all"

Read your HOST NAME + PRIMARY DNS SUFFIX.

My DNS SUFFIX was emtpy so i went and added using this link
http://www.simpledns.com/kb.aspx?kbid=1227

And then rebooted the machine.

Now the code works like a charm. Thanks BEN !!!