Webmail users will be forced to change their password when they login to webmail (when the password has expired).
Users will also be notified via email before the password expires. The system administrator can set the dates before expiration that a user will be notified. By default those notifications are sent out 28, 14, 7, 3, 2 and 1 day(s) before their password expires. So accounts that do not use webmail will get plenty of notifications before their outgoing messages get blocked.
We don't have a video for this.