SMTP Error Codes| senders.yahooinc.com
The Authenticated Received Chain (ARC) protocol provides an authenticated "chain of custody" for a message, allowing each entity that handles the message to see what entities handled it before and what the message's authentication assessment was at each step in the handling. ARC allows Internet Mail Handlers to attach assertions of message authentication assessment to individual messages. As messages traverse ARC-enabled Internet Mail Handlers, additional ARC assertions can be attached to mes...| IETF Datatracker
Valimail's commitment to enhancing the scalability, visibility, and security of our DNS infrastructure.| Valimail -
Sender Best Practices for mail deliverability| senders.yahooinc.com