1. Open the computer first, then open the outlook2007 version on the desktop of the computer, and then log in to the mailbox. Click "File" in the upper left corner of the page, and a dialog box will pop up. Click "Options".

2. In the Outlook option setting box that pops up on the screen, please click the "Mail" option in the left menu bar.

3. Then, in the mail setting box on the right, please find and click the "letters and fonts" option.

4. Click "Font" under the new email on the left, select the required font size in the new pop-up box, and then click the "OK" button below.

5. You will jump to this interface and click OK in the lower right corner to complete the font size setting.