Apple 550/554 5.7.1 CS01
Policy rejection
Policy rejection means the receiving provider rejected the message for a provider-specific reason. Use the diagnostic text before deciding on retries or suppression.
Observed with both 550 and 554 wrappers. Match the CS01 token rather than one exact outer reply code.
Decision
Do not retry unchanged. Fix the sender setup first.
Confidence: high. Recipient validity: unknown.
Match this reply
- SMTP stage
- End of DATA
- Endpoint
- Inbound MX
[CS01]local policyStart here
- 1
Review the provider diagnostic text for the specific policy that was triggered.
- 2
Do not keep retrying unchanged if the reply is permanent. Fix the sender, content, or recipient policy first.
Confirm the cause
- Review recent sending volume, bounce rate, complaint rate, and list hygiene for this provider.
- Confirm SPF, DKIM, and DMARC alignment so reputation problems are not made worse by authentication failures.
- Resume with lower provider-specific volume only after deferrals stop or the provider accepts test mail.
App handling
- Treat this as a sender setup incident, not a bad recipient.
- Hold similar mail for the same sender domain or provider until the fix is verified.
- Retry after a fresh single-recipient test succeeds.
Avoid
- Do not retry unchanged in a loop.
- Do not suppress the recipient unless the text explicitly says the mailbox is invalid.
- Do not treat a permanent SMTP code as proof that the address is bad; policy and routing failures can also be permanent.
Common causes
- Volume increased faster than the provider trusts for this sender.
- Recent bounces, complaints, or low engagement damaged sender reputation.
- The provider applied a traffic, content, or sender policy to protect recipients.
Developer details
Fields to log
raw SMTP replyremote MX or hostSMTP stagereply codeenhanced codeprovidermatched rule idrecipientsending domaindecisiontimestamp