A 440 Login Time-out error is an unofficial HTTP status code defined by Microsoft Internet Information Services (IIS), particularly within Outlook Web Access (OWA) and Microsoft Exchange Server environments.
It indicates that the user’s authenticated session has expired after a period of user inactivity, and the server requires re-authentication before further requests can be serviced.
Determining why
Microsoft Exchange and IIS web applications maintain inactivity timers to protect user mailboxes and enterprise portals from unauthorized access when a computer is left unattended. When the timer lapses, subsequent web requests receive a 440 status and redirect to the login screen.
Steps you could possibly take:
- Log back in - Refresh the page and re-enter your username and password.
- Check for cookie blocking - Ensure your browser allows authentication cookies from your corporate email domain.
- If you are an Exchange / IIS administrator:
- Adjust forms-based authentication inactivity timeout thresholds in the Exchange Admin Center (EAC) or IIS management console.
Source: Microsoft Exchange Server Documentation - Forms-Based Authentication Timeouts