554 delivery error: dd This user doesn't have a yahoo.com account

The recipient address does not exist at Yahoo. Yahoo phrases its unknown-user bounce without an enhanced status code, which confuses parsers that expect 5.1.1, but it means the same thing: there is no mailbox, and there is nothing to fix on the sending side.

What the server replies

554 delivery error: dd This user doesn't have a yahoo.com account (tom.becker@yahoo.com) [0] - mta4356.mail.ne1.yahoo.com

Sent by
Yahoo and AOL
Type
PermanentRetry fails
About
Recipient problems
Enhanced code
None sent

Who sends it

Yahoo and AOL mail transfer agents after the message has been accepted, as a delivery status notification. The "dd" tag and the mta hostname identify Yahoo's delivery layer. Yahoo rejects some unknown users at RCPT TO with 550 5.1.1 too; this wording comes from the later stage.

Why it happens

  • A typo in the address.
  • Yahoo deleted the account after a long period of inactivity, which it does after about a year.
  • An old list containing addresses that were abandoned years ago.
  • The address exists at ymail.com or rocketmail.com but was entered with the wrong domain.

How to fix it

  1. Suppress the address

    Treat it as a hard bounce and stop sending. Yahoo converts some abandoned addresses into spam traps, so continuing to mail unknown users is how senders end up with TSS09.

  2. Verify before re-adding

    If the person contacts you again, add the address they write from rather than the one that bounced.

  3. Clean the list

    A send with more than a percent or two of these means the list is old. Run it through verification before the next campaign.

Related codes

Sources

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