Email Listener does not create emails and the following error is logged in EmailService.frslog: Failed to obtain authentication token for tenant HEATAPPmscorlib|System.Web.Services.Protocols.SoapException: Access denied. at CentralConfig.ConfigServiceAPI.AuthenticateAPI(String userName, String tenantId)
When IPv6 is not enabled, the Operating System can enable the "Teredo Tunneling Pseudo-Interface" and create a dynamic IPv6 address after restarting, so this IP will not be present in the Trusted IP Addresses list.
The solution will be enabling IPv6 for having a fixed address, and then add the address to the Trusted IP Address list (ConfigDB tenant).
This screenshot corresponds to the server when IPv6 is not enabled, we can see how anyway there is an IPv6 configured: