@Leanne_T Yes, deleting everything seems to have solved it. Are you any closer to solving the fault so it doesn't reoccur?
To clarify, it is the people who receive emails from me who get the big font size. They end up writing back to say they can't read it.
Thanks for letting me know @adam101
I have fed this back to the relevant team, if this does happen again please come back and let me know.
Leanne.