Peterandrew,

See if the following method allows you to save your changes.

• Select Tools | Options... from the menu.
• Go to the Mail Format tab.
• Click Fonts... under Stationery and Fonts.
• Use the Font... buttons under New mail messages, Replying or forwarding messages and Composing and reading plain text messages to choose the desired font faces, sizes and styles.
  • In Outlook 2003, use Choose Font... for When composing a new message:, When replying and forwarding: and When composing and reading plain

Hope this helps.