Most of our customer client sites are ClassicASP running on a separate web server and they use CDOSYS (IIS-SMTP) to open a connection to our SmarterMail server as any old "SMTP Client" -- authentication is possible, and TLS can be used as well in this setup if your mail server responds with a valid certificate.
I have a ton of ClassicASP code that accomplishes this but it's part of a mini-framework used for client websites and would take a little "cleanup" to send you samples.
If you setup basically a blank .ASP page, and add Server.CreateObject("CDO.Message") and run it -- if it doesn't throw an exception, you have all you need (other than some code) to have SMTP via ClassicASP.
CDO uses a Message and Configuration object to function properly - both are needed.
MailEnable survivor / convert --