When an email is automatically forwarded by an inbox rule this results in a soft bounce event because of an authentication failure.

ARC, or Authenticated Received Chain, is an email authentication protocol that addresses the limitations of SPF, DKIM, and DMARC when emails are forwarded or pass through intermediaries such as mailing lists or forwarding services.

At present, Mailjet does not support ARC signing. The platform fully supports SPF, DKIM, and DMARC authentication, which cover the vast majority of delivery scenarios. However, ARC is a newer protocol, primarily designed to preserve authentication results when messages are forwarded or relayed through intermediaries such as mailing lists or automated forwarding systems.

ARC can help mitigate issues like false bounces or DMARC failures in these specific forwarding cases, although industry adoption of ARC is still developing.