Why does Yahoo report a closed account when Kickbox says deliverable?

Email marketer from Mailjet explains that discrepancies between deliverability and validation can occur because validation services provide a snapshot in time, while actual deliverability depends on real-time factors like recipient engagement and inbox provider filtering. An email address deemed valid by a validator may still bounce if the mailbox is full or inactive at the time of sending.

Email marketer from StackOverflow shares that email address validation methods such as checking the syntax and domain name can only verify that the email address conforms to a valid format and exists at a particular point in time. It cannot determine if an email address is currently active or able to receive emails.

Email marketer from LinkedIn suggests that Yahoo bouncebacks can be misleading, and that the reported error is not always the specific cause of the bounce. They suggest validating with multiple services.

Marketer from Email Geeks shares that they would trust the actual mailbox provider over a verification service because the verification services are using cached results from bought bounce results.

Email marketer from ZeroBounce explains that the email verification process includes syntax check, domain check, and MTA validation, however it does not guarantee future deliverability. An email address might be valid at the time of verification but later become invalid due to factors like inactivity, user flagging it as spam, or a change in the recipient's email settings.

Marketer from Email Geeks explains that any list service bases its score on things they or their partners have seen. It's possible the address was deliverable when the cleaning service last saw it. Since then the mailbox could have been disabled and that Yahoo disables inactive mailboxes, and provides a link to Yahoo Help about inactive mailboxes.

Email marketer from Reddit explains that email validation services rely on techniques that aren't foolproof and that a mailbox might appear valid but reject emails due to antispam measures or temporary issues. The email ecosystem is constantly evolving and that validation services will never be 100% accurate.

Email marketer from EmailToolTester explains that they share the limitations that while email validation tools can help you clean your email list of invalid addresses, they are not perfect. They share that the information on an email address can change quickly, so it’s important to regularly clean your list.

Email marketer from Email Marketing Forum shares that Yahoo is notorious for ambiguous bounce messages. A 'disabled' message doesn't always mean permanently closed, but can indicate temporary issues, spam filtering, or inactivity. The poster also suggests checking Yahoo's bulk sender guidelines.

Email marketer from NeverBounce shares that email validation services check syntax, domain existence, and spam traps, but can't guarantee inbox placement. Real-time deliverability depends on sender reputation, content, and recipient interaction, factors not evaluated by validation alone. A mailbox may be temporarily unavailable, leading to a bounce despite validation.

Expert from Word to the Wise explains the importance of feedback loops from mailbox providers like Yahoo. They highlight that Yahoo, like other providers, uses feedback loops to provide senders with information about complaints and bounces. They also mentions that understanding and acting on feedback loops can improve deliverability.

Expert from Spamresource.com advises on the importance of having bounce processing set up correctly so that you get accurate bounce messages. They don't talk specifically about Yahoo vs Kickbox, but inaccurate bounce messages can be caused by bad bounce processing.

Expert from Email Geeks says that they would generally trust the mailbox provider over the third-party vendor.

Expert from Word to the Wise shares an article on the importance of email list hygiene and cleaning. They note that even validated lists degrade over time, leading to deliverability issues, and underscores the need for ongoing maintenance beyond initial validation. Factors for why emails are not delivered include the email address being closed or blocked after the last validation.

Documentation from SparkPost shares that they categorize bounces as either temporary or permanent failures and that temporary bounces could be a result of the user being temporarily unavailable. An account can be temporarily disabled.

Documentation from Yahoo Help explains that Yahoo may disable inactive mailboxes after a period of inactivity. This can lead to bounces even if the address was previously valid. The specific timeframe for disabling accounts isn't explicitly stated, but it's a common practice to free up resources.

Documentation from RFC Editor describes SMTP error codes which highlights that 5xx errors mean permanent failures. A 550 error, which is common, means the mailbox is unavailable for policy reasons. This can happen for a number of reasons including inactivity or spam filters.

Documentation from Amazon Web Services differentiates between hard and soft bounces. A hard bounce indicates a permanent reason an email cannot be delivered, such as a non-existent address. A soft bounce indicates a temporary issue, such as a full mailbox or the server being temporarily unavailable.