Our email verification service encounters an error when testing with Yahoo email addresses. The error message we receive is:
553 5.7.2 [TSS09] All messages from 106.196.118.124 will be permanently deferred; Retrying will NOT succeed. See https://postmaster.yahooinc.com/error-codes
This error indicates that Yahoo’s mail server is rejecting messages from our IP address (106.196.118.124) due to a specific issue (TSS09). We need assistance in understanding the root cause and resolving it.
We’ve reviewed Yahoo’s error code documentation (linked in the error message) but need further guidance on interpreting it. We’ve checked our email configuration, SPF records, and DKIM settings but the issue persists. We expected successful email delivery to Yahoo recipients.