After nearly a year and multiple threads on this one issue alone this thread was supposed to be escalated to an Engineer. A forum moderator replied who claims to be a support specialist replied. I can honestly say Microsoft has finally driven me away from PCs and into a Mac.  Some as basic as a font setting was designed to keep the user settings!!! If we're lucky some techy outside of Microsoft will create a work around but I'm not staying! A dedicated Hotmail user of over decade has finally been driven away! RonielD and his post:
 "Roniel_D. replied on

Forum Moderator Community Star Community Star
Hi Everyone,

I'm Ron a support specialist, I'm sorry for the inconvenience this issue caused you.

I would like to inform you that this is by design as HTML formatting is being used.

This usually happens when you delete the entire paragraph resulting to deleting the tagging information at the beginning of that paragraph that defines the font and attributes of the paragraph.

 

Furthermore - if the you uses [CTRL+Enter] for line breaks instead of just using Enter; you will retain font information across line breaks when moving to new paragraphs.


Thank you for your feedback,

Regards,

Ron"

You'll find the thread here: http://answers.microsoft.com/en-us/windowslive/forum/mail-email/writing-e-mail-font-size-changes/7c9c2cdc-457b-4f38-8a42-2ad5a219cad9?page=7&tm=1376652139119