formatting errors in hotmail

I use formatting (bold, size, color) options in  e-mails being sent in Outlook thru my Hotmail account.  Often the formatting is changed in the body of the e-mail after I hit the "send" button.  These changes are not consistent as to what part of the message changes or what they're like.  Part of a sentence will be changed from a color to black.  Size of font in a line will be reduced. Bold deleted, etc.  If I compose the e-mail in WORD and copy/paste it into the message, the formatting sometimes changes there too.  What needs to be done to keep the formatting the way I want it????