In VS2013, I've added a reference to the Mail.dll. Then in my classes I do this:
using Limilabs.Mail; using Limilabs.Mail.MIME; using Limilabs.Mail.Headers; using Limilabs.Client.SMTP;
Intellisense at that point recognizes Limilabs and I can see the Limilabs classes in Intellisense auto-complete suggestions. However, when I try to Run with Debugging, I get an error:
Error 2 The type or namespace name 'Limilabs' could not be found (are you missing a using directive or an assembly reference?)
Why can't the dll be found?
The only article I can point you to is MSDN help (How to: Add or Remove References By Using the Add Reference Dialog Box): https://msdn.microsoft.com/en-us/library/wkze6zky(v=vs.120).aspx
Mail.dll is standard .NET assembly, it works like any other assembly you use.