[GTM glossary](/glossary.txt) Hard bounce Sales Development & Prospecting # Hard bounce In short A hard bounce is a permanent failure to deliver an email. The receiving server rejects the message because the address does not exist, the domain is invalid, or the server refuses all mail from the sender. Hard bounces matter because mailbox providers read them as a sign of poor list quality. Too many hurt your sender reputation and can push later emails to spam, so outbound teams remove these addresses at once. ## Common causes of hard bounces * **Address does not exist:** A typo, or a person who left the company and had their mailbox deleted. * **Invalid domain:** The domain is misspelled, expired, or has no mail server. * **Blocked sender:** The recipient server permanently rejects your domain or IP. * **Guessed addresses:** Emails built from name patterns without verification often hit missing mailboxes. --- ## What to do when an email hard bounces ### Suppress the address Add it to a suppression list so no sequence ever sends to it again. Most email platforms do this automatically; confirm that yours does. ### Find the cause Read the bounce code. A "user unknown" response means the mailbox is gone. A policy or block response points to a reputation or authentication issue on your side. ### Look for a replacement contact If the person left, find who now holds the role and add them. A bounce can be a useful signal of job change. --- ## How to prevent hard bounces * **Verify before sending:** Run lists through email verification before they enter a sequence. * **Refresh old data:** Contact data decays as people change jobs, so re-check older lists. * **Watch the rate:** Say you send 1,000 emails and 30 hard bounce. That is a 3 percent rate, which most teams would treat as a warning to clean the list. Check your provider for its own limits. * **Authenticate your domain:** Set up SPF, DKIM, and DMARC so legitimate mail is not rejected. --- ## Hard bounce vs. soft bounce A hard bounce is permanent and means stop sending. A soft bounce is temporary, such as a full inbox, and the address may work later. --- ## Hard bounce FAQs **What is a hard bounce in email?** A hard bounce is a permanent delivery failure. The receiving server rejects the email because the address is invalid, the domain does not exist, or the server blocks the sender. These addresses should be removed from your lists immediately. **What causes a hard bounce?** Typical causes are mistyped or nonexistent addresses, deleted mailboxes after someone leaves a company, invalid or expired domains, and permanent blocks by the recipient server. Unverified, guessed, or old list data raises the risk significantly. **Is a hard bounce bad for deliverability?** Yes, repeated hard bounces signal poor list hygiene to mailbox providers. That can damage your sender reputation and send more of your future emails to spam. Verifying addresses and removing bounces quickly keeps the risk low. **How do you fix a hard bounce?** You cannot retry the same address, so remove it from your lists and read the bounce message for the reason. Correct obvious typos, find a replacement contact if the person left, and verify future lists before sending. Share term --- ## More related phrases * [Soft bounce](/glossary/soft-bounce.txt) * [Email service provider](/glossary/email-service-provider.txt) * [Reply rate](/glossary/reply-rate.txt) ## Similar phrases * [Bounce rate](/glossary/bounce-rate.txt) Bounce rate is the percentage of sent emails that are rejected by the recipient's mail server and never reach an inbox, split into hard and soft bounces. * [Email verification](/glossary/email-verification.txt) Email verification tests whether a specific email address is likely to accept mail, helping teams cut bounces, protect sender reputation, and avoid wasting outreach on dead addresses. * [Email deliverability](/glossary/email-deliverability.txt) Email deliverability is your ability to get emails into recipients’ inboxes instead of spam or being rejected, shaped by reputation, authentication, and content. * [Sender reputation](/glossary/sender-reputation.txt) Sender reputation is the trust score mailbox providers assign to your sending domain and IP, which affects whether your emails reach the inbox or spam. * [Email bounce rate](/glossary/email-bounce-rate.txt) Email bounce rate is the percentage of sent emails that are not delivered to the recipient, and it signals list quality and sender health.