What causes "too old" bounce messages and how to fix high bounce rates from Verizon (Yahoo, AOL)?

Email marketer from ActiveCampaign answers that to improve and maintain email list health, focusing on list hygiene is vital, which consists of removing inactive or unengaged subscribers from your email list. In addition, they share that you can focus on your sender reputation as this ensures that your email provider knows that you are credible.

Email marketer from MailerLite shares that reducing your bounce rate involves validating email addresses before sending. They suggest using email validation services, cleaning your list of unengaged subscribers, and only sending to subscribers who have explicitly opted in to receive your emails. Segmenting your lists and personalizing emails can also help improve engagement and reduce bounces.

Email marketer from Sendinblue explains that high bounce rates are detrimental to sender reputation and deliverability. They identifies hard bounces (permanent reasons like invalid addresses) and soft bounces (temporary issues like full inbox or server problems). Solutions include regularly cleaning lists, using double opt-in, authenticating email with SPF/DKIM, and monitoring sender reputation.

Marketer from Email Geeks shares that their issue was resolved when Customer.io and Verizon worked together to fix a change on Verizon's side. They stayed on a shared IP and suggests asking the ESP to reach out to Outlook or see if others are having the same issue, as it might be a larger problem.

Email marketer from Neil Patel explains that Yahoo, AOL, and Gmail implemented stricter guidelines to protect their users from spam. Email senders now have to use email authentication methods like SPF, DKIM, and DMARC to prove that they are credible.

Email marketer from Reddit mentions, in a forum discussion, that when experiencing high bounce rates on a shared IP, it's important to contact the email service provider (ESP). The ESP can investigate whether the issue is widespread or specific to the user's account. They also recommend checking if there's been a recent change in the ESP's policies or infrastructure.

Email marketer from StackExchange answers to never use an old mailing list straight away without checking the emails are valid. They explain that you can use an email verification service for the first send, so you can remove non-existent emails and help make sure you don't get blocked by any mail servers.

Email marketer from EmailOctopus Blog explains that a high bounce rate indicates problems with your email list or sending practices. Possible causes include sending to invalid or non-existent email addresses, using outdated or purchased lists, or having deliverability issues. To fix this, they recommend cleaning your email list, implementing double opt-in, and authenticating your email.

Expert from Word to the Wise, Laura Atkins, explains that AOL/Verizon’s “too old” bounces are often due to aggressive greylisting and rate limiting, especially for senders with a less-than-stellar reputation. She advises that if bounces are related to '421' or 'resource unavailable', the solution may be to throttle the email flow and retry later. She also explains, high complaint rates are often a root cause, so managing sender reputation by optimizing opt-in processes, content relevance, and list hygiene can help to avoid or mitigate being classified as a poor sender.

Expert from Spamresource explains that AOL and Yahoo Mail are implementing new email authentication requirements for senders. As of now, they recommend that all senders authenticate their email with SPF, DKIM, and DMARC, and to make it easier for users to unsubscribe.

Expert from Email Geeks explains that "Too old" bounce messages generally mean that the ESP has been trying to deliver the email for a certain amount of days (3-4) without success. Microsoft has declined to accept the email each time. If it's selectively affecting the user's mail and not others on the shared IP, it's likely related to how Microsoft customers are reacting to the mail. The expert suggests looking at permission collection methods and recipient expectations, then pausing sending and warming up again.

Documentation from SparkPost explains that bounces are classified into hard and soft bounces. Hard bounces indicate permanent delivery failures (invalid email), while soft bounces are temporary issues (server unavailable). They emphasize that managing bounce rates and addressing the causes are important for deliverability.

Documentation from RFC describes SMTP Enhanced Mail System Status Codes. These codes are returned by mail systems to indicate the outcome of a mail delivery attempt. They provide a standardized way to communicate the reason for bounces, including permanent and transient errors.

Documentation from AWS explains that monitoring bounce and complaint rates is essential for maintaining a good sender reputation. AWS provides tools for tracking these metrics and recommends taking action when rates exceed acceptable thresholds. They advise setting up feedback loops and processing bounce notifications to remove invalid addresses from your sending list.