If you happen to receive phishing emails or spam directly in your Inbox (not spam emails from the junk email folder), you can report the mail in two ways:
Microsoft guarantees to catch 98% of all incoming spam, and that fewer than 1 in 250,000 is a false positive.
A false positive is an email which Microsoft marks as spam but which you did not consider to be spam. This only works on email in the Junk folder.