gmail.com is rejecting emails from Microsoft Exchange 2010 and Microsoft Exchange 2013 email servers for no PTR records even if you do not have any IPv6 IPs assigned to the server.
The sender does not meet basic ipv6 sending guidelines of authentication and rdns resolution of sending ip. Please review https://support.google.com/mail/answer/81126for more information.
Your message wasn't delivered due to a permission or security issue. It may have been rejected by a moderator, the address may only accept email from certain senders, or another restriction may be preventing delivery.
Diagnostic information for administrators:
Generating server: EXCHANGE.a51.biz
mx.google.com #550-5.7.1 [ipv6info] The sender does not meet basic 550-5.7.1 ipv6 sending guidelines of authentication and rdns resolution of 550-5.7.1 sending ip. Please review 550 5.7.1 https://support.google.com/mail/answer/81126 for more information.
Disable certain IPv6 components yourself, follow these steps:
- Use the registry editor to edit the following path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters\
Verify that IPV6 is disabled with the following command: "reg query HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters /v DisabledComponents"
- Edit or create DWORD (32-bit) value "DisabledComponents".
- Default value is "0", you will need to change this to "0xffffffff"(Hexadecimal "ffffffff" or Decimal "4294967295") in order to disable all IPV6 other than local loopback.
- You may receive the following error message: "ERROR: The system was unable to find the specified registry key or value."
- If you receive this error message, the DisabledComponents registry value is not set. If the DisabledComponents value is set, it overrides the settings in the connection properties.
If you have IPv6 IP's enabled on the server verify that your PTR records are correctly setup.