I believe that this information is also available on the Microsoft Exchange Hosted Services site, but I thought I'd repost it here.
When making spam submissions, copy the original headers from the email (in Outlook, right-click the message and select Message Options) and forward the message, pasting in the headers at the top of the email. Send the message to email@example.com.
False positives are for messages that were incorrectly filtered as spam. Either salvage the message from Spam Quarantine or from the Spam Notification that you get in your email account. Messages that were filtered as a result of Custom Spam Filtering are not eligible to be submitted as false positives because that is an option that your company has enabled; it is not us who blocked it using our global anti-spam rules.
All questions about particular email messages should be directed to firstname.lastname@example.org. I can answer questions about the general nature of spam and spam trends but not about specific spam issues with regards to individual submissions.