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Error code wiki · 7 codes

Yahoo and AOL SMTP error codes

Yahoo runs Yahoo Mail and AOL Mail on one platform, so mail to yahoo.com, aol.com and the other domains it hosts faces the same sender rules and error codes.

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Permanent failures (5xx)

5 codes

The receiving server refused the message for good. Your server will not try again, and the message comes back to you as a bounce.

  1. 550Refused for a header or address problem.Yahoo or AOL refused the message for a policy reason tied to its headers, its addresses or the sending domain's DNS. Yahoo lists these as other policy errors, sent as 550 or 554.Permanent
  2. 553Permanent rejection (553).Yahoo or AOL rejected the message for good with a 553. Yahoo groups 553 with 554 as its permanent errors, so retrying will not help until the cause is fixed.Permanent
  3. 554Permanent rejection (554).Yahoo or AOL rejected the message for good with a 554. Yahoo uses this code for several problems, from failed authentication to unacceptable content, so the wording of the reply tells you which.Permanent
  4. 554Failed authentication.Yahoo or AOL refused the message because it failed the checks that confirm the sending domain, such as DKIM against the domain's policy. Yahoo lists this among its permanent 553 and 554 errors.Permanent
  5. 554Recipient does not exist.The Yahoo or AOL account you wrote to does not exist. The failure is permanent: check the address with the recipient, and remove it from any list.Permanent

Temporary failures (4xx)

2 codes

The receiving server cannot take the message now. Your server keeps it and retries, and only bounces it if the retries run out.

  1. 421Temporary error or deferral.Yahoo or AOL refused your message for now with a 421, one of its two temporary error codes. Your server should keep it and retry; repeated deferrals point to reputation or complaints.Temporary
  2. 451Sender domain could not be resolved.Yahoo could not confirm that the domain in your envelope sender or From address exists. As a 451 it is temporary; Yahoo can also return the same problem as a permanent 554.Temporary

Every code in the wikiPaste your own bounce

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