The days of leaving the front door unlocked are gone, as are having an insecure Pa$$word. This is your first and most important line of defence.
Office 365 Provides the following options:
- Force users to change passwords on a regular basis.
- Enable Multi Factor Authentication
Like some banks multi factor authentication makes you enter a code from a txt message when you enter your password. Providing two forms of identification. Yes it’s a pain.. but it’s secure and can be turned on for select people only.
It’s also worth reviewing your list of users. If staff have left or are on extended leave, mark them as not able to login. Check also if your support partner has access to your account and what their password policies are.