First of all, if you are thinking Outlook Express, just forget it. The only three ways of integrating with Outlook Express are (and this is just my guessing) by paying Microsoft a lot of money and by giving them a really good reason to why you want to do that, or by hooking in through the encryption-entry, or by creating a proper hook and hacking your way in there. I've done the hacking (due to missing funds) and it's not a pretty sight, it works but it's everything from clean.
