CA certificates trusted by Gmail for S/MIME
This list of trusted certificates provided and maintained by Google applies only to Gmail for S/MIME. The list of CAs are trusted solely at Google's discretion and Google retains the right to remove root CAs at will, with or without reason. Important : At least one intermediate CA certificate must be present in the chain.
How to know the device type using MAC address?
This is generally not possible. Using the MAC address, you can look up the maker of the Bluetooth radio. That's it. Sometimes, this can give a strong hint at the type. However, if a device is close enough for mutual data exchange, you will eventually get their name and device type using the so-called Inquiry process.