What does a hard bounce user unknown [5.0.0 SMTP reply matched bounce-rcpt pattern rule] mean?

Email marketer from Reddit shares that a hard bounce often means the email address is no longer valid, the domain might not exist anymore, or the recipient's server has blocked the sender. They recommend immediately removing these addresses from the mailing list.

Email marketer from Email Geeks explains that the bounce message is from the ESP and the actual SMTP response should be requested from them to understand the real reason for the bounce.

Email marketer from Constant Contact shares that keeping your contact lists clean and up-to-date to avoid hard bounces will improve your sender reputation. Removing non-existent email addresses improves email deliverability.

Email marketer from ActiveCampaign explains that hard bounces are permanent delivery failures. A key reason is an invalid email address. Removing hard bounces from your lists is crucial to maintaining a healthy sender reputation.

Email marketer from SparkPost shares that a hard bounce signals a permanent reason for delivery failure, such as an invalid email address. This invalid address is most likely the case when 'User Unknown' is returned.

Email marketer from SendGrid shares that a hard bounce means the email address is invalid or doesn't exist. This can be due to typos, domain issues, or the recipient's server blocking delivery. Hard bounces should be removed from your mailing list to maintain a good sender reputation.

Email marketer from MailerQ shares that 5xx errors indicate that the mail could not be delivered. This is a permanent error and that you should not try to deliver the mail again to the same recipient. A "User unknown" is often caused by a typo in the recipient's address, or the user may have left the company.

Email marketer from Stack Overflow answers that a 'User Unknown' error (often represented by a 550 code, which falls under the 5.X.X category) indicates that the email address you are trying to reach does not exist on the recipient mail server. The user may never have existed, or the account may have been closed.

Email marketer from Email Geeks explains that `dsnstatus` is made up, `dsndiag` is what Google told the delivering MTA. Also, Tim Starr says Yes, that looks like a miscategorization of the bounce code from the receiving MTA. It should be a 4.x.x bounce, not 5.0.0. Some 5.0.0's are hard, some not, but this isn't any kind of 5.x.x bounce at all, much less a 5.0.0.

Email marketer from Tech Support Forum explains that SMTP error codes beginning with '5' signal a permanent failure. The 'User Unknown' message usually means the email address does not exist at the recipient's domain. This is a typical hard bounce reason.

Expert from Email Geeks clarifies that over quota bounces at Google tend to be temporary (signaled by a 452 code) and suggests ensuring that the subscriber isn't removed from future sends due to the misclassification. Ideally, monitor the address for subsequent sends to confirm the quota issue is resolved.

Expert from Email Geeks shares that real Google bounces end with "-gsmtp", and if that's missing, it's not a genuine Google bounce.

Expert from Word to the Wise shares that receiving a 'user unknown' error means the email address doesn't exist. Regular list cleaning, including the removal of hard bounces, is essential for maintaining deliverability and avoiding being flagged as a spammer.

Expert from Spam Resource explains that a 'user unknown' hard bounce indicates a non-existent email address and that maintaining list hygiene by removing these addresses is crucial for sender reputation. They emphasize proactive list management to avoid sending to invalid recipients.

Expert from Email Geeks explains, based on the description from Pardot, the system got a SMTP reply that matched one of their bounce handling rules and was classified as a user unknown. Headers are not helpful when trying to diagnose a delivery failure because they mean there was no delivery failure.

Expert from Email Geeks suspects that recipients (or their companies) might have marked the sender as unwanted, causing a permanent-failure "unknown user" bounce in an attempt to get the sender to remove them from the audience.

Documentation from RFC 3463 explains that the first digit '5' of a DSN (Delivery Status Notification) code indicates a permanent failure. The second digit indicates the class of failure, and the third provides detail. A 'User Unknown' error falls under this permanent failure category.

Documentation from Oracle explains that a hard bounce is a permanent failure to deliver email, generally caused by a non-existent or invalid email address. It is important to remove these from your email list as the email is undeliverable.

Documentation from MDN Web Docs explains that a 5.0.0 status code in SMTP indicates a permanent failure. The email server encountered a critical error and was unable to deliver the message. Further attempts to send the email will likely result in the same failure.

Documentation from AWS explains that a hard bounce means the recipient's email address is invalid. This could be because the domain name doesn't exist, or because the recipient is unknown. They advise immediately stopping sending to these addresses.

Documentation from Microsoft explains that a non-delivery report (NDR) with a 5.x.x error code indicates a permanent error. A common reason is 'recipient address rejected: User unknown in virtual alias table'. This means the email address does not exist in the organization.