This happens because when you are composing email in Outlook and the format is HTML, every time you hit enter, it adds a paragraph break; i.e. it adds a </P> and starts the next line with a <P>. If you then view the resulting message in Outlook, it looks fine, but when viewed in Gmail, Yahoo!, etc., etc. those </P> tags are converted to extra line breaks.

The only solution is for the person composing the message in Outlook to hit Ctrl+Enter instead of just Enter; Outlook then inserts a standard line break (<BR> tag) instead of a </P>.

The other solution is for Microsoft to FIX THIS... that will probably be a long wait.