Relevant Products: Signature Manager Outlook Edition
After disabling TLS 1.0 or SSL 3.0 in your Exchange environment for security compliance, the OWA signatures fail to update and the following error messages are logged in the Exclaimer Application event logs in Event Viewer on the server or PC where Signature Manager outlook Edition is installed:
Microsoft.Exchange.WebServices.Data.ServiceRequestException: The request failed. The underlying connection was closed: An unexpected error occurred on a receive. ---> System.Net.WebException: The underlying connection was closed: An unexpected error occurred on a receive. ---> System.ComponentModel.Win32Exception: The client and server cannot communicate, because they do not possess a common algorithm.
When disabling TLS 1.0 or SSL3, it is necessary to ensure TLS 1.2 is enabled for .NET Framework version 4.x as per the following instructions.
Enable TLS 1.2 for .NET 4.x
- From Notepad.exe, create a text file named NET4X-UseSchannelDefaults.reg.
- Copy, and then paste the following text.
Windows Registry Editor Version 5.00
- Save the NET4X-UseSchannelDefaults.reg file.
- Double-click the NET4X-UseSchannelDefaults.reg file.
- Click Yes to update your Windows Registry with these changes.
- Restart your computer for the change to take effect.
Note: It is necessary to ensure that TLS 1.2 is enabled and configured on both the Exchange server and the machine where Signature Manager Outlook Edition is installed.
These steps are taken from part 2 of the following 3 part series of articles explaining how to correctly enable and configure TLS 1.2 for EWS in an Exchange environment:
Part 1: https://blogs.technet.microsoft.com/exchange/2018/01/26/exchange-server-tls-guidance-part-1-getting-ready-for-tls-1-2/
Part 2: https://blogs.technet.microsoft.com/exchange/2018/04/02/exchange-server-tls-guidance-part-2-enabling-tls-1-2-and-identifying-clients-not-using-it/
Part 3: https://blogs.technet.microsoft.com/exchange/2018/05/23/exchange-server-tls-guidance-part-3-turning-off-tls-1-01-1/