Gmail is rejecting mails because of ipv6 information in the mail header

The solution is On all exchange servers (mailbox, hub, cas) add this to the registry and reboot the servers hkey_local_machine\system\currentcontroset\services\tcpip6\parameters\ add entry Reg_dword disabledcomponents with decimal 255

Dont disable ipv6 on the nic, just add the record to registry. Disabling IPV6 on the nic will also disable exchange