In order to improve Panel security, you can set the minimum password strength (in Tools & Settings > Password Security > Password strength) for all passwords in the system. Password strength is a measure of how effectively a password is resistant to various types of attacks. Generally, the strength of a password depends on its complexity and overall length.
When any Panel user (the administrator, a customer, reseller, or auxiliary user) sets a new password in Panel (for example, creates a new mail account or changes the password of an FTP user), they are required to adjust the password until it meets the minimum password strength. Note that if you increase the minimum strength, already existing passwords will not be affected by new requirements.
We recommend that you force your users to employ stronger passwords, though, note that such passwords are harder to remember.
Panel distinguishes five levels of the password strength which allow you to get the right balance between required protection and password complexity: Very weak, Weak, Medium, Strong, and Very strong.