SMPT and Smart Mail

Ok, so how do I send EMail to a smart mail account through my website using smtp. I am using exist .NET 2.0 code that works with non Smart Mail.

 

I setup an EMail Account using the Smart Mail server.

Then from a contact form written in C# .NET 2.0. System.Net.MailAssembly. I try EMailing using SMTPto the EMail Account. It comes back tells me to try again in 900 ms. The very same code works fine on other Discount ASP Site that I work with that do not use Smart Mail. I tried using a thread to wait the required time. But this is unaccectable to the client and appears to be unreliable method.