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Email Marketing Glossary.

Clear, no-fluff definitions of every email marketing term that matters—from open rates to double opt-in. 

 

Hard Bounce

A hard bounce is a permanent email delivery failure — typically because the address is invalid or doesn't exist. Hard-bounced addresses should be removed from your list immediately.

Also known as: permanent bounce

A hard bounce is email's version of a return-to-sender stamp that says "this address will never work." Unlike a temporary glitch, it won't resolve on its own — the address is simply bad.

What causes a hard bounce?

Common causes include a mistyped or fake address, a domain that doesn't exist, or a mailbox that's been permanently closed. Purchased and old lists produce lots of hard bounces.

Why do hard bounces matter?

Mailbox providers treat repeated hard bounces as a sign you don't maintain your list, which damages your sender reputation and deliverability. Most platforms automatically suppress hard-bounced addresses.

How do you prevent hard bounces?

Use double opt-in, validate addresses at signup, never buy lists, and remove hard bounces right away. Good acquisition habits keep them rare.

Related terms

Email Deliverability Sender Reputation SPF DKIM DMARC

Related reading from Drip

What Happens to Bounced Emails? (Help Center) 7 Proven Ways to Reduce Email Bounce Backs

Frequently asked questions

What is a hard bounce?
A hard bounce is a permanent email delivery failure, usually because the recipient's address is invalid, mistyped, or no longer exists. The address should be removed from your list immediately.
What causes a hard bounce?
Invalid or fake email addresses, non-existent domains, and permanently closed mailboxes. Purchased or outdated lists are a common source of hard bounces.
What's the difference between a hard and soft bounce?
A hard bounce is a permanent failure that won't resolve, while a soft bounce is temporary — like a full mailbox or a down server — and may succeed on a later attempt. Hard bounces should be suppressed right away.
How do I prevent hard bounces?
Use double opt-in, validate addresses at the point of signup, avoid buying lists, and remove hard-bounced addresses immediately. These habits keep your list clean and protect your reputation.
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