Hi Stefan,
As i understand this update fix issue with email messages. In our case , email alerts when new user is added to SharePoint group is not working. And any alert on list/library is not working as well. Emails from workflows ( nintex ) are working.
Error in logs: SSL policy errors have been encountered.Error: Exception while sending email: System.Security.Authentication.AuthenticationException: The remote certificate is invalid according to the validation procedure.
Does this looks like the error which can be fixed with May update /
Thank You