HTML email with Outlook

Hi, I've made a PHP script that sends out an automatic email through my servers cron system, it works well, but I thought I'd try to do some HTML email to get things to line up a little better. To do so, I added the following line in my mail() command: -Type: text/html; charset=iso-8859-1 When I check the messages sent out with Eudora, the HTML email comes in perfectly. However, when I check with Outlook Express 6 - I get the actual HTML code rather than the nicely formatted email that I had created. Should I be using another line in my mail() command? I've recieved HTML email before with Outlook Express on my machine without changing any settings at all. Also, I had sent an email from my script to hotmail and the HTML email worked fine there too. Any thoughts? Thanks -Tim