What is the ARC protocol used for?

The Authenticated Received Chain ARC (Authenticated Received Chain) protocol enhances email security by preserving authentication information throughout the transmission chain, even when messages are relayed or forwarded. Its main functions include:

• Preserving original authentication:
  When an email passes through intermediary services such as mailing lists or forwarding tools, authentication mechanisms like SPF, DKIM, and DMARC may be altered or lost. ARC ensures that this information remains intact, making message filtering more reliable.
• Maintaining trust:
  Intermediary servers add ARC headers to confirm that authentication checks were performed and that the results remain trustworthy, even after forwarding.
• Improving email deliverability:
  By preserving the integrity of authenticated messages, ARC reduces the risk of emails being marked as spam or rejected after passing through multiple servers.

ARC plays a key role in combating spam and email spoofing attacks while improving the reliability of email communications.