Your Account Settings page allows you to add or change email addresses, as well as change your email notifications. By default, your primary email is set to your @army.mil email address.

Change default iPhone and iPad apps under Settings > Apps > Default Apps. Options include browsers, messaging, contactless apps, and autofill setups for password managers. You can't pick a new default ...

If you often have to manually change the "From" field to a different email address, you can eliminate this hassle by adjusting the default account in the Mail settings. To do so, open the Settings ...