Email Bounce Code Decoder

Read what a bounce message actually says, and whether it will retry.

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Common codes
  • 4.2.2 — The recipient mailbox is full.
  • 4.4.1 — No answer from the receiving server.
  • 4.4.2 — The connection was dropped mid-delivery.
  • 4.7.0 — Temporarily deferred by a policy — commonly greylisting or rate limiting.
  • 4.7.1 — Delivery temporarily refused for policy reasons.
  • 5.1.1 — The mailbox does not exist at that domain.
  • 5.1.2 — The domain does not exist or has no mail servers.
  • 5.1.8 — The sender address is invalid or its domain does not exist.
  • 5.2.1 — The mailbox exists but is disabled.
  • 5.2.2 — The mailbox is full, and the receiver treats that as permanent.
  • 5.4.1 — No answer from the destination and the receiver has given up.
  • 5.7.1 — Delivery refused by policy — relaying denied, blocked sender, or failed authentication.
  • 5.7.13 — The sending account is not permitted to send as that address.
  • 5.7.26 — The message failed authentication — no aligned SPF or DKIM.
  • 5.7.509 — The receiver could not authenticate the sender and requires DMARC alignment.

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