Why are deliverable users getting hard bounces and marked as undeliverable?

Email marketer from Reddit shares that ESPs may incorrectly classify temporary issues as hard bounces due to aggressive bounce rules. It is important to monitor and manually review bounce reports.

Email marketer from GlockApps explains that while not a direct cause, landing in spam traps or blocklists can indirectly cause deliverable users to get hard bounces. Regular list hygiene and sender reputation monitoring are key.

Email marketer from Postmark responds that overly aggressive spam filters at the recipient's end might misclassify legitimate emails as spam, resulting in hard bounces. Implementing feedback loops can help identify and address deliverability issues.

Email marketer from Email Marketing Forum explains that the recipient's server might be experiencing temporary technical difficulties, or the sender's IP address may have been temporarily flagged as suspicious.

Email marketer from Email on Acid suggests reasons could include recipient firewalls temporarily blocking emails or the sending IP address being temporarily blacklisted. Implementing email authentication protocols such as SPF, DKIM, and DMARC is critical.

Email marketer from Litmus shares that email verification tools, while helpful, are not foolproof, and temporary delivery issues can still lead to valid addresses bouncing. Testing email deliverability with various mailbox providers can identify potential problems.

Email marketer from HubSpot explains that although hard bounces typically represent permanent delivery failures, temporary server issues or incorrectly configured firewalls can lead to legitimate addresses being incorrectly flagged. Regular list cleaning and verification are essential.

Email marketer from Sendinblue shares that reasons for hard bounces include invalid email addresses, typos, and outdated contact lists. Cleaning lists regularly is recommended.

Email marketer from Neil Patel shares that reasons include outdated email lists, spam traps, and recipient server issues. High bounce rates negatively impact sender reputation.

Expert from Email Geeks suggests talking to Responsys about making changes to their hard bounce process. Mentions that some folks might be able to help craft an argument for the changes.

Expert from SpamResource explains that sometimes the interpretation of bounce messages by the sending server is incorrect, leading to an address being marked as a hard bounce when it's actually a temporary issue.

Expert from Word to the Wise shares that improper bounce processing and overzealous filtering by ESPs can contribute to deliverable users being marked as undeliverable. Analyzing bounce codes and understanding the nuances of server responses are critical.

Expert from SpamResource explains that temporary rejections (greylisting) can sometimes be misinterpreted as permanent failures by systems that are not configured to handle them properly, leading to valid addresses being marked as undeliverable.

Expert from Email Geeks asks for clarification on the definition of a 'hard bounce' as there are different interpretations, some meaning the address is undeliverable, and others meaning the email is undeliverable.

Expert from Email Geeks advises to see if Responsys will show the rejection messages from the recipient mailbox provider when they suppress an address due to a hard bounce, to gain understanding of the rejections and the reasons behind Responsys' policy.

Expert from Email Geeks states that ESP misclassifying a rejection is definitely a possibility and advises to check the rejection message to see if that's what's happening and to see the actual reason for the rejection.

Expert from Email Geeks suggests that the issue could be related to smaller mailbox providers being less reliable and bouncing emails occasionally, or that Responsys' bounce classification is more accurate at larger mailbox providers.

Expert from Email Geeks explains that there's no such thing as soft or hard bounces in email, these are made up by ESPs. He also advises to check the rejection message from the ESP when a hard bounce occurs to understand why it happened.

Expert from Email Geeks mentions that smaller providers might use blocklists, and the sender could be on a shared blocklist like Spamcop or Mimecast.

Expert from Email Geeks says that a USER_NOT_FOUND classification strongly suggests the user doesn't exist, and that's seldom a temporary state. Recommends looking at the actual rejection messages.

Documentation from Mailgun clarifies that hard bounces occur when an email is permanently undeliverable due to reasons like a non-existent address or a blocked sender. However, server misconfigurations can sometimes cause temporary issues to be incorrectly classified as hard bounces.

Documentation from Amazon SES details that while hard bounces usually indicate permanent issues, temporary server problems or filtering rules can occasionally cause valid addresses to bounce. Monitoring bounce notifications and investigating patterns is important.

Documentation from SparkPost explains that a hard bounce indicates a permanent reason an email cannot be delivered, such as a non-existent email address. However, misconfiguration or outdated information can lead to false hard bounces.