A hard bounce means an email address is invalid or can no longer receive emails permanently. This is different from a soft bounce, which is usually temporary.

• Invalid email address: the address is misspelled (e.g. john@gnail.com) or the account no longer exists. This often happens with old lists or addresses that were never active.
• Non-existent domain: the part after the @ sign is invalid or has been shut down, for example because a company closed or the domain is no longer in use.
• Blocked by the server: the recipient's mail server is rejecting your emails. This can happen because your domain or sending address is on a blacklist, or because the recipient has explicitly blocked your domain.

You don't have to do anything yourself. Xendy automatically recognizes hard bounces and blocks these addresses immediately — the contact receives the status Bounced and will no longer receive emails. This way you prevent sending to non-existing addresses and protect your sending reputation from damage.

Hard bounces directly affect how providers like Gmail and Outlook judge your emails. The lower your hard bounce rate, the better your chances of landing in the inbox. That's why Xendy automatically makes sure hard bounced addresses are never emailed again.