.The OFT to HTML converter offers more functionality, including the ability to convert OFT emails to HTML without any technical knowledge.

This OPML to HTML via Javascript tool also parses OPML you copy and paste into it and creates clickable links on a web page. Sadly, this page is not save-able, but it does support OPML folders.

They follow up with tips on turning some or all emails to plain text. If you're generally emailing inside a closed circle with Outlook users, HTML-formatted emails are probably fine.