What causes Yahoo to return TSS09 error and how to resolve it?

Email marketer from Mailgun Support notes that DMARC failures can lead to TSS09 errors. Ensuring SPF and DKIM are properly configured and aligned with the sending domain is crucial for passing DMARC checks.

Email marketer from EmailGeeks Forum suggests checking the SMTP bounce message for a link to Yahoo's sender support page. They recommend opening a ticket with Yahoo or having the customer correct their sending practices.

Email marketer from Stack Overflow shares that TSS09 errors often stem from poor list hygiene. He recommends implementing strict opt-in procedures, regularly cleaning the email list to remove inactive or invalid addresses, and honoring unsubscribe requests promptly.

Email marketer from Reddit suggests that high complaint rates can trigger TSS09 errors. He advises monitoring feedback loops (FBLs) to identify and remove subscribers who mark emails as spam, thereby improving sender reputation.

Marketer from Email Geeks shares that the SMTP bounce message should include a link to Yahoo's sender support page, suggesting opening a ticket or addressing the sending practices. The link provided is <https://senders.yahooinc.com/smtp-error-codes>.

Email marketer from Litmus mentions sender reputation as a key factor. Building and maintaining a positive sender reputation through consistent sending practices, engagement, and authentication is vital for avoiding delivery issues like TSS09.

Email marketer from Email on Acid points out that spammy content can trigger TSS09 errors. Reviewing email content for potentially problematic keywords, excessive use of images, and proper HTML formatting is important.

Expert from Word to the Wise explains that Yahoo TSS09 errors can be caused by a number of issues including low engagement, sender reputation problems, or potential blocklisting. She emphasizes proactive monitoring of sender reputation and engagement metrics to avoid triggering such errors.

Expert from Email Geeks highlights the key points regarding 5XX permanent errors from Yahoo's sender best practices, including invalid email addresses, authentication failures (DMARC/DKIM), unacceptable message characteristics, suspicious behavior, or IP listing by Spamhaus. He advises against retrying sending emails with 5xx errors and recommends list managers remove such addresses.

Expert from Spamresource notes that sender reputation issues frequently cause blocks like the Yahoo TSS09. Improving reputation involves consistent authentication, list hygiene, engagement metrics, and avoiding spam traps.

Documentation from Yahoo Postmaster recommends reviewing their sender best practices guidelines to ensure compliance. Key areas include authentication (SPF, DKIM, DMARC), list management, content quality, and engagement monitoring.

Documentation from Spamhaus indicates that a TSS09 error might be related to the sender's IP being listed on Spamhaus. Senders should check their IP reputation on the Spamhaus website and follow their delisting procedures if necessary.

Documentation from RFC 5321 (SMTP standard) explains that 5xx errors are permanent failures, indicating the message could not be delivered and should not be retried. While TSS09 isn't a standard code, it falls under this category, signaling a permanent delivery issue.

Documentation from Yahoo Help Center explains that a TSS09 error means 'All messages from your IP address will be permanently deferred.' It typically indicates a severe sending issue, such as spam-like content, very low engagement, or poor IP reputation. Resolution requires addressing the underlying sending practices and potentially opening a support ticket with Yahoo.