I am unable to connect the Out-of-Office (DSOF) to my Exchange 2016 server. When I choose to add End-Point and fill the dialog with username and password and click Okay, I just get "establishing a secure TLS/SLL channel failed".
On further investigation I find that we have disabled the TLS1.0 + 1.1 protocol on our Exchange server, just like Microsoft advised recently. Office 365 is also soon going to move to 1.2 only.
Do you have an update to your product?
TLS is happening at the transport layer of .NET. So it is not something that is controlled by DynamicSignature. So you should ensure that the machine you installed DSOF on supports TLS1.2. Below is a copy of an article written by Microsoft that guide you to enable TLS1.2 in both the OS and .NET.
Reboot is required.