Unless you are using the .NET framework you'll need an additional library of functions. Here's a free one. I haven't tried it, so I can't recommend it personally, but you can find others via Google (try "C++ email").
Personally I would use the .NET framework which makes this sort of thing a breeze.
I would go with ijack, check any platform specific library like .NET or generic POP3/SMTP ones (again, the one suggested bu ijack seems good). C++ by itself comes with very little APIs to do that kind of stuff, I think that is why people were so happy to leave it behind for Java and .NET.