Learn how to troubleshoot when requests placed via the Services add-in and pre-registered visitor lists are not following meeting rescheduling and cancellations.
One of the main requirements for using the Services and Visitor Management modules is to have TLS 1.2 enabled and selected both for inbound and outbound traffic (both for client and server requests) in your Exchange Servers. Using older versions of TLS, such as 1.0, or 1.1 will prevent your requests and visitor pre-registrations from following any modifications made to meetings (such as rescheduling and cancellations), thus making the meeting management process more difficult.
In order to make the requests and pre-registered visitor lists to follow changes made to the meetings (re-scheduling or cancellations), please enable and select TLS 1.2 both for inbound and outbound traffic (both for client and server requests) in your Exchange Servers.
The following guidance from Microsoft contains instructions for how to do so, and it goes step-by-step through the process of making sure TLS 1.2 for outbound traffic on HTTPS is enabled.