Hard Bounce

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Definition

A hard bounce is a permanent email delivery failure that occurs when an email cannot be delivered due to a permanent reason, such as an invalid email address, non-existent domain, or blocked recipient. Hard bounces should be removed from your list immediately.

Common Causes of Hard Bounces

Invalid or misspelled email addresses (john@gmial.com)

Non-existent domains (user@companythatclosed.com)

Deleted or deactivated email accounts

Blocked recipients who have marked you as spam

Typos in the domain name or username

Why Hard Bounces Matter

Hard bounces directly damage your sender reputation. Email providers track your bounce rate, and high rates signal that you're not maintaining a quality list. A bounce rate above 2% is concerning, and above 5% can result in blacklisting. Each hard bounce is a warning sign that needs immediate action.

How to Handle Hard Bounces

Remove hard bounces from your list immediately after each campaign

Never send to an address that has hard bounced

Verify email addresses at the point of collection

Use email verification services to clean your list proactively

Monitor bounce rates and investigate sudden spikes

Frequently Asked Questions

What is the difference between hard and soft bounces?

Hard bounces are permanent failures (invalid addresses, non-existent domains) that require immediate removal. Soft bounces are temporary issues (full inbox, server down) that may resolve on their own. After 3-5 consecutive soft bounces, treat them as hard bounces.

What is an acceptable hard bounce rate?

Keep hard bounce rates below 0.5% per campaign. If you're seeing rates above 2%, you have a list quality problem. Regular email verification can reduce hard bounces to near zero.