outlook font size when replying to emails

[quasimodem]

So I have a user who is going blind (i guess) and can't read size 10 font and wants his email to automatically change to size 12 when ever he replies to any emails sent to him.

I've looked but can't figure out how to make it the default to all replies, anyone have any ideas?

It's outlook 2003.

Thanx
QM