In a network configuration where a message could not be delivered because there is a partner connector configured that matched the message's recipient domain, and the connector has either restrictdomainstoipaddresses or restrictdomainstocertificate set, what is the most likely cause of the delivery failure?
A) The recipient server's IP address is not included in the connector's allowed IP addresses.
B) The recipient domain's DNS records are incorrectly configured.
C) The message exceeds the maximum allowed size for the recipient server.
D) The sender's domain is not properly authenticated with the recipient's mail server.