The reason that ESXi 6 is not listed as supported is because at this time the email appliance has not been fully 100% tested for compatibility. I am not aware of any reason that the email appliance will not work on ESXi 6.
The reason that ESXi 6 is not listed as supported is because at this time the email appliance has not been fully 100% tested for compatibility. I am not aware of any reason that the email appliance will not work on ESXi 6.