Why is Yahoo deferring my emails with a TSS04 error and high bounce rate?
Summary
What email marketers say7Marketer opinions
Email marketer from Reddit user u/EmailExpert shares that sending a significantly higher volume of emails than usual can trigger deferrals. Gradually increasing volume over time is recommended.
Email marketer from EmailAnalytics shares that a high bounce rate can be caused by sending emails to invalid or inactive email addresses. Cleaning your email list regularly can improve your sender reputation and reduce bounce rates.
Email marketer from LinkedIn states that proper authentication is key, including SPF, DKIM and DMARC, to ensure a secure email platform.
Email marketer from EmailOnAcid explains that a poor IP reputation can cause email providers such as Yahoo to defer emails. You can check your IP reputation with online tools.
Email marketer from Mailjet notes that user complaints, such as marking emails as spam, can negatively impact your sender reputation and lead to deferrals. Monitoring and addressing complaints are essential.
Email marketer from StackOverflow user User456 explains that spam filters can be triggered by certain keywords, phrases, or formatting in email content. Reviewing content for potentially problematic elements is recommended.
Email marketer from EmailGeek Forum advises that DMARC implementation is important and helps Yahoo identify that you are a legitimate sender. Making sure DMARC, DKIM and SPF records are setup can avoid being marked as Spam
What the experts say5Expert opinions
Expert from Spam Resource explains that a TSS04 error usually means that Yahoo is temporarily blocking your emails because of a perceived problem with your sending habits, email content or volume. It is recommended to check the content and volume of email sent.
Expert from Word to the Wise, Laura Atkins, explains that if your bounce rate is caused by spam traps it can cause problems with deliverability. She also mentions that having very old data can mean that some of your list has now become spam traps.
Expert from Email Geeks advises wrapping bare YouTube URLs with click tracking to see if it resolves the issue. Suggests reviewing MTA settings to avoid aggressive practices like opening too many connections.
Expert from Email Geeks explains that the issue is unlikely related to authentication problems and suggests it could be due to a sudden increase in email volume or user complaints. He recommends checking the actual rejection messages for more details.
Expert from Email Geeks suggests examining the email content, including the reputation of domains linked within the message body, as they can contribute to rejections. Mentions that URLs with past complaint history can be flagged.
What the documentation says5Technical articles
Documentation from Google Postmaster Tools indicates that high spam complaint rates signal problems with email content, sending practices, or list quality. Monitoring spam rates helps identify and resolve issues.
Documentation from Yahoo Postmaster explains that a TSS04 error indicates that messages from your sending server are temporarily deferred due to unexpected volume or user complaints. It suggests reviewing the Yahoo Postmaster guidelines for best practices.
Documentation from Microsoft explains that they have sending limits to protect against spam. Make sure your limits are not exceeded.
Documentation from SparkPost explains that deferrals are temporary rejections. The mail server might retry sending the email later. High deferral rates may indicate issues with IP reputation or content.
Documentation from RFC5321 regarding SMTP states that a 421 response code from a mail server indicates the service is unavailable. The sending MTA should retry later.