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Yahoo Inc SMTP 553 Errors: Every Bounce Response Explained

Every SMTP 553 response on record from Yahoo Inc (yahoo.com, aol.com, verizon.net), with the verbatim text, the enhanced status code, a severity rating and a plain-English fix.

The mailbox name is not allowed, usually because the address is malformed, the domain is wrong, or the receiver will not accept mail addressed that way.

Provider
Yahoo Inc
Code
553 (5xx)
Responses
2
Highest severity
Medium

Yahoo Inc SMTP 553 responses

Status 5.7.1Medium severity#
host xx.yahoodns.net [x.xx.xx.xx] SMTP error from remote mail server after MAIL FROM:<[email protected]> SIZE=2022: 553 5.7.1 [BL21] Connections will not be accepted from x.xx.xx.xx, because the ip is in Spamhaus's list; see http://postmaster.yahoo.com/550-bl23.html

The sending IP or domain is on a blocklist the receiver checks, so mail stays refused until the listing clears. Find which list flagged you, fix the underlying cause, then request removal. Delivery can stay blocked for up to a day after delisting while caches refresh.

Provider documentation

Status 5.7.1-2Medium severity#
host xx.yahoodns.net [x.xx.xx.xx] SMTP error from remote mail server after MAIL FROM:<[email protected]> SIZE=2022: 553 Mail from x.xx.xx.xx not allowed - 5.7.1 [BL23] Connections not accepted from IP addresses on Spamhaus XBL; see http://postmaster.yahoo.com/errors/550-bl23.html [550]

The sending IP or domain is on a blocklist the receiver checks, so mail stays refused until the listing clears. Find which list flagged you, fix the underlying cause, then request removal. Delivery can stay blocked for up to a day after delisting while caches refresh.

Provider documentation

Postmaster & documentation

Yahoo Inc SMTP 553 questions

›What does an SMTP 553 error from Yahoo Inc mean?

The mailbox name is not allowed, usually because the address is malformed, the domain is wrong, or the receiver will not accept mail addressed that way. At Yahoo Inc, it is a permanent rejection, and the specific reason is in the enhanced status code and message text of each response below.

›How do I stop Yahoo Inc from returning SMTP 553?

Match your bounce text to one of the responses below and follow its guidance. Recipient-side wording means fix the address. Authentication or reputation wording (SPF, DKIM, DMARC, blocklist) means fix your sending setup, and check Yahoo Inc's postmaster documentation.

All SMTP 553 responsesAll Yahoo Inc error codes

Other error codes seen from Yahoo Inc