
Explanation/Reference:
Explanation:
The maximum number of days you can set the 'Days before password expire' to is 730. This will make the password valid for the longest duration.
To be notified as early as possible on that the password is about to expire, we should set the maximum value, which is 30, to the ' days before users are notified that their password will expire' setting.
Note: Set a user's password expiration policy
Sign in to Office 365 with your work or school account.

Go to the Office 365 admin center.

Go to Service settings > Passwords.

If you don't want users to have to change passwords, select Passwords never expire. If you select this

option, users won't get any reminders anymore to change their passwords.
If you want user passwords to expire, type the number of days before the password should expire.

Choose a number of days from 14 to 730.
Type the number of days before users are notified that their password will expire, and then click Save.

Choose a number of days from 1 to 30.
References:
https://support.office.com/en-us/article/Set-a-users-password-expiration-policy-0f54736f-eb22-414c-8273-
498a0918678f