Microsoft Outlook, the email client in Microsoft's Office widely used suite of productivity applications, offers users a variety of options to customise the experience of reading, writing and organising e-mail messages. One of the simplest ways to customise e-mails in Outlook is to change the font or font size used in e-mail messages. Permanently changing the font size of e-mails in Microsoft Outlook is not difficult to do, thanks to a simple set of menu options.
Click the "Tools" menu at the top of your screen, then select "Options."
Click the "Mail Format" tab, and then select the "Stationery and Fonts" tab.
Click "Personal Stationery." View options to change the font and font size of e-mails you compose, read, reply to or forward to someone else.
Click the "Font" button for the changes you would like to make. For example, to change the font size for e-mails you compose to others, click the "Font" button below the New Mail Messages option.
Select the new font size you would like from the pop-up box. Click "OK" on this pop-up box, on the Stationery and Fonts box, and on the Options box.
Choose a common font when you change your font in Microsoft Outlook; according to Microsoft, recipients will not be able to read your message properly if you choose a unique font that they do not have.
Note that font size changes that you indicate in Microsoft Outlook will only apply to plain text e-mails. Messages in HTML format cannot change font size this way because of limitations in the coding of the email.