This is not strictly a VC++ issue, anyway I'm facing this problem in one of my VC++ projects, so please help me.

My program sends emails using IIS SMTP service on Windows 2000 Server.
Users with an account on hotmail or yahoo get the email on their spam box, which is something they're no used to.

Most users simply give up, others ask about it, very few find the email in the spam box.
How can I make my emails come in the correct folder?

Thanks in advance.