What does the Apple 554 5.7.1 [CS01] error mean?
Summary
What email marketers say11Marketer opinions
Email marketer from Mailjet explains that 5.7.1 often means the message was blocked due to security policies, content filtering, or reputation issues.
Email marketer from Stack Overflow shares that 5xx errors indicate a permanent delivery failure. 5.7.1 usually means general delivery failure.
Marketer from Email Geeks explains, based on prior understanding, that it's a content issue via ProofPoint.
Marketer from Email Geeks remembers that this might be a content block.
Email marketer from Reddit explains that Apple's privacy relay can sometimes cause bounceback issues if the receiving server has strict anti-spam measures.
Email marketer from Email Vendor Guide Forum indicates the Apple 554 error may relate to the content triggering spam filters, possibly from a certain word or phrase.
Email marketer from SuperOffice Blog explains that a 5.7.1 error indicates a general delivery issue. They advise checking sender reputation, IP address on blocklists, and content for spam triggers.
Email marketer from Litmus Community suggests that the error could stem from personalized content triggering filters, especially if a specific subset of recipients encounters the error.
Email marketer from Postmark explains that Apple 554 5.7.1 indicates a permanent delivery failure, often caused by content issues or SPF/DKIM issues.
Email marketer from MailerQ explains that an SMTP reply code in the 500s indicates permanent failure. Code 5.7.1 means that the email was rejected because of an issue with content.
Marketer from Email Geeks suggests that CS might mean Content Scanner.
What the experts say2Expert opinions
Expert from Email Geeks clarifies it's not IP or domain-based but could be content-related, perhaps triggered by personalized content. Also suggests it might be a block at the forwarding domain if it's an Apple privacy protection address.
Expert from Word to the Wise explains that a 554 error, particularly with a 'CS' code, indicates the email has triggered content scanning filters, likely due to specific keywords or patterns identified as potentially harmful or unsolicited.
What the documentation says3Technical articles
Documentation from Cisco explains 5.7.1 as 'Delivery not authorized, message refused', often due to sender restrictions or policy violations by sender or content.
Documentation from Proofpoint Support explains that the 'CS' code within the 554 5.7.1 error typically refers to a Content Scanning issue. This means the email was blocked due to its content being flagged by Proofpoint's content filters.
Documentation from RFC 5321, the standard for SMTP, broadly defines 5.7.1 as 'Security policy rejection'. This means that the receiving server considers the email a violation of its security policies.