Apple

4.7.0

iCloud closed the session after too many SMTP errors. Fix the underlying reject, then reconnect and retry.

4.7.1

iCloud deferred this mailbox because it is receiving mail too quickly. Wait and retry. Spread sends if many land on the same address.

4.7.1

iCloud is not accepting mail right now, often during peak top-of-hour traffic. Wait a bit, then retry at a steadier rate.

5.1.1

iCloud says this mailbox does not exist. Check for typos, then remove it if it is still wrong.

5.7.1

Apple blocked this under a local filter policy. Follow Apple's sender guidance, then contact their postmaster with logs if it persists.

5.7.1-2

Apple rejected this under your domain DMARC policy. Align SPF or DKIM with the From domain so DMARC passes, then resend.

5.7.1-3

Apple rejected a URL that appears on the Spamhaus DBL. Delist the domain with Spamhaus, then wait for caches to refresh before retrying.

5.2.2

This iCloud mailbox is over quota. Retry later, or ask the recipient to free space.

5.7.1

Apple rejected this under a local policy. Ask the recipient to mark you as a VIP contact, or contact Apple postmaster with logs if it keeps failing.

5.7.1

Apple rejected this under a local policy. Ask the recipient to mark you as a VIP contact, or contact Apple postmaster with logs if it keeps failing.