>We would like to add the ability to send e-mails in our application can anybody give me a idea were to start. Is it using Outlook Express or MAPI ??

You have multiple choices. You can use MAPI, but you may be limited by the security features. Or you can choose to communicate via SMTP(skipping Outlook) and talk directly to the mail servers.

There are a few different components manafacturers that may suit your needs.
My company is one of them.

I have an article that might help describe for you how to send emails:
http://www.seekfordsolutions.com/Articles/HowToSendEmailFromYourProgram.asp