Choosing the correct font and font style for your email messages is important. It denotes your own personality in a way. However, the font and styles can change due to an upgrade to the Office program or Windows updates, which include updates to the Office program.
To resolve this frustrating issue, for new messages, open Outlook. Click the File Tab, then Options, then Mail. Under the heading Compose Message, click Stationary and Fonts. Look for Personal Stationary tab and under the heading New mail messages click Font. On the Font tab and under the term Font look for and choose your font. You can also choose a style and size. Click Ok three times, (you are moving out of the windows you just opened), to change the default values.
For reply or forwarding messages: return to the Stationary tab and select Replying or forwarding messages. Then click Font and follow the above directions again.