Why are cox.net email addresses soft bouncing and showing bounce errors?
Summary
What email marketers say12Marketer opinions
Email marketer from GMass explains that soft bounces are a result of the receiving server seeing something that it does not like, but the message is not permanently rejected. There is likely a temporary issue such as a policy configuration.
Email marketer from Email Geeks reports a spike of 'Recipient address rejected: User does not exist' bounces, and expert from Email Geeks confirms it may be a false bounce.
Email marketer from MailPoet Blog explains that soft bounces often indicate temporary problems with the recipient's server, such as being overloaded or temporarily unavailable. Retrying delivery later may succeed.
Email marketer from Quora explains that soft bounces may occur when there are issues with the recipient's server, such as it being overloaded, undergoing maintenance, or having temporary anti-spam measures in place. This can cause emails to be temporarily rejected.
Email marketer from Email Geeks shares that there have been some LDAP issues earlier in the week at Cox.net.
Email marketer from Email Geeks shares that email delays with cox.net have increased over the past week and bounce rates have also increased.
Email marketer from Sendinblue explains that soft bounces can result from server outages or full mailboxes. It's a temporary delivery failure, and subsequent attempts may succeed.
Email marketer from Stack Overflow user states that 4xx errors are temporary issues and retry is needed, and you should implement exponential backoff retry mechanism.
Email marketer from Email Geeks reports seeing block bouncing at cox.net intermittently throughout the week.
Email marketer from EmailOctopus explains that a soft bounce might occur because the recipient's inbox is full, the server is down, or the message size is too large. These are generally temporary issues.
Email marketer from Reddit explains that increased soft bounces to a specific domain like cox.net could indicate a temporary issue with their mail servers, such as increased spam filtering or server maintenance.
Expert and email marketer from Email Geeks discusses 550 errors being reported, even for engaged addresses. James offers to investigate further with details like IPs and error messages.
What the experts say3Expert opinions
Expert from Email Geeks shares that others have reported issues with cox.net email addresses in the last 24-48 hours, indicating something is happening at Cox, but the cause is unclear.
Expert from Spam Resource explains that bounces can occur due to reputation issues with your sending IP or domain, causing receiving servers (like those at cox.net) to temporarily reject or defer your email.
Expert from Spam Resource suggests that a 'Deferred' message in email logs indicates a temporary issue at the recipient's end (e.g. cox.net). The receiving server is either overloaded or experiencing temporary problems that prevent immediate acceptance of the email.
What the documentation says3Technical articles
Documentation from Amazon Web Services explains that a soft bounce indicates a temporary delivery issue such as a full mailbox or a server being unavailable. Amazon SES recommends handling soft bounces differently than hard bounces.
Documentation from Microsoft states that 4.X.X SMTP enhanced status codes indicate a transient failure, which may not be permanent, and the message may be able to be sent in the future.
Documentation from ietf.org defines a 4.X.X series Delivery Status Notification (DSN) code which generally indicates a temporary failure. This can include issues like server overload or connection problems. Soft bounces often result from such temporary failures.