.NET is out there
There is a FAQ on the ASP.NET Forum pinned by Mike and mainly focus on the FAQs for Email Sending in ASP.NET, and Dave also created a web site dedicated in this topic recently!
System.Web.Mail, OH MY! Complete FAQ for the System.Web.Mail namespace
the number one item there imho is the one about walking the exception stack-trace! when web.mail blows up it's often needed to dig way down the stack to find the "real" exception data.
Yes, I agree with you. E.g. Just an exception like "Could not access 'CDO.Message' object" imply a few of possible causes...