highlight the text where you want to change the font. the default font is calibri (body) 11, but you can change this. About press copyright contact us creators advertise developers terms privacy policy & safety how works test new features press copyright contact us creators. when i change this to calibri 12 in outlook preferences the change holds until i exist out of outlook. the default font for new mail, replies forwards, and plain text is set at calibri 11. I have an ongoing issue with outlook 2016 for mac (15.23) that is driving me crazy. for example, click font next to new mail to select a default font for new messages, or next to reply or forward to set a font for outgoing messages. in the default fonts for composing messages section click the font button next to the composition style you want to edit.