This idea has been merged into another idea. To comment or vote on this idea, please visit NTS-I-34 Add a zoom functionality.
Users whose having issues reading emails with small or default font sizes would like to increase the font size when viewing received emails. They do not want to change the Windows OS scaling and would like to only increase the font in the email body and keep all other fonts the current size.
Since changing the UI preference settings can only change the font size of the body of the emails' sent internally, they need this new option to help user to modify the font size of the email's body sent by external users as well.