One of the ways that Office 365 for small business protects you, is requiring the users to type in a password when they sign in. As an Office 365 admin, you need to manage passwords for your organization. By default, password expires for 730 days, but as an admin, you can change how often passwords expire.
- On the admin page, under Service Settings click Passwords.
- On the right side, type in the number of days you want the passwords to stay valid.
- Click Save.
Fourteen days before a password is set to expire, the user is set to receive a reminder to change the password.