Password expiration is a quite frequent cause of many IT support issues. Passwords that are not changed within required timeframes can cause help desk calls from users, productivity losses, and sometimes disruptions of critical services.
 
Windows automatically notifies users during interactive logon, but in some cases-for example, when users have AD accounts only for VPN, Outlook Web Access (OWA), file shares - users would never actually log on interactively and see this standard Windows notification.

The Password Expiration Notifier application is a small tool that will periodically check all users in the specified Active Directory domain or OU to detect ones whose passwords are about to expire in a specified number of days, and then sends customizable notification e-mails to the account owners. The tool also sends summary reports to system administrators by e-mail. Armed with this tool, administrators can proactively resolve password expiration issues for end-users and service accounts.

The Password Expiration Notifier also includes the "Plan & Test" feature which allows you to verify your configuration and see how many users will be affected by planned password policy changes without disturbing the users and changing AD settings.

NOTE:  Password Expiration Notifier is now part of the Netwrix Auditor Freeware Edition suite which allows you to install the application as a standalone tool.