If 451 redirect URL is set up on your ActiveSync server, Standalone Sentry handles the redirection when a device tries to sync. The redirect URL is not forwarded to the device.
You configure 451 redirect processing on the Ivanti Standalone Sentry by enabling or disabling the Enable Redirect Processing (451) field in the Edit Standalone Sentry page. From the Admin Portal, go to Services > Sentry, and click on the edit icon for the Sentry. Redirect processing is enabled by default. To disable redirect processing clear the checkbox next to Enable Redirect Processing (451).