How to write a SMTP program?

How to write a simple SMTP program, anyone can help?
Any place or website that I can refer?

http://members.dingoblue.net.au/~privoli/SMTPSample.vbw
http://members.dingoblue.net.au/~privoli/SMTPSample.vbp
http://members.dingoblue.net.au/~privoli/SMTPSample.frm