@SolusVM See reply post from @Olivia_Rust at EMC Support on this subject
Olivia_RustLeader
Hello Ossopite,
it is actually the standard to add the device name to the Message ID to assure the ID is indeed unique and other desktop clients should use this standard.
Sender domain is used when you create/send your message through webmail (because it does not have information about your device name).
If you are concerned about your privacy, perhaps change the device name to something neutral.
Regards,
Olivia