A hard bounce is an email that is permanently rejected because the recipient address is invalid — the mailbox does not exist, the domain is wrong, or the server has permanently blocked delivery. Unlike a soft bounce, a hard bounce will never succeed, so the address should be removed from your list immediately.
Hard bounce vs soft bounce
A soft bounce is a temporary failure (a full mailbox or a server that is briefly unavailable) and may deliver on retry. A hard bounce is permanent. Repeatedly mailing addresses that hard-bounce signals careless list hygiene to mailbox providers and drags down your sender score.
Why hard bounces matter
A high hard-bounce rate hurts deliverability and can get you flagged or blacklisted. Keeping it low — by using confirmed sign-ups and cleaning your list — protects inbox placement. Learn more in our guide to email bounces and the bounce types that matter.
How Mailpro handles hard bounces
Mailpro detects hard bounces automatically and stops sending to those addresses, so your stats stay clean and your reputation protected. See how bounce management works. Related: bounce rate and email blacklist.
Mailpro and bounce management
Keep bounces from wrecking your deliverability
Mailpro detects and removes hard bounces automatically and shows them in your stats, so your list stays clean and your sender reputation stays high.