Once you've set up your account in Mail for Windows 10, you don't have to enter your password every time you open the app. If the password for your email account expires or you change it for security purposes, you may need to update your password in the Mail app.
Update a password
If you've changed your password with your email provider, you can update the stored password in Mail for Windows 10.
Choose Settings > Manage Accounts, and then choose the account you need to update.
If you selected an Outlook.com account, you can change or update your password by choosing Change account settings. Mail for Windows 10 will take you to a webpage for your account where you can change your password. After you update the password on the webpage, Mail for Windows 10 will receive that change automatically.
For all other accounts, you can update the password in the Account Settings dialog box and then choose Save.
If your password has expired or you think your account has been compromised, you'll need to change your password with your email service provider—for example, Gmail or iCloud—before you update the password in the Account Settings dialog box.
If Mail for Windows 10 won't accept your new password, make sure Caps Lock is turned off, and then reenter your password.