What is Hard Bounce?
TL;DR
An email returned because the address is permanently undeliverable, the address doesn't exist, the domain is invalid, or the server explicitly rejected you. Unlike Soft Bounces, hard bounces won't resolve with retry. Hard bounced addresses should be immediately removed from your Email List; continuing to send to them damages Sender Reputation. High hard bounce rates (over 1%) indicate list quality problems: old data, typos at signup, or purchased lists. Reduce hard bounces with real-time email validation at signup (typo detection, format checking), Double Opt-In, regular list cleaning, and never buying lists. Email platforms track and automatically suppress hard bounces, but the damage to your reputation from the initial bounce remains. Prevention through quality list-building is the only real solution.
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Frequently Asked Questions About Hard Bounce
What causes a hard bounce?
The email address doesn't exist, the domain is invalid, or the server explicitly blocked you. Unlike soft bounces, hard bounces are permanent, retrying won't help. The address simply cannot receive email.
Should I try sending to hard bounces again?
Never. The address is permanently undeliverable. Continuing to send damages your sender reputation. Email platforms automatically suppress hard bounces, don't manually re-add them.
What's an acceptable hard bounce rate?
Under 0.5% ideally. Over 1% indicates serious list quality problems. Even a single campaign with high hard bounces damages your reputation for future sends. Prevention is essential.
How do I prevent hard bounces?
Validate email format at collection (catch typos), use double opt-in (verify addresses work), never buy lists, clean old lists before mailing, and use email verification services for questionable addresses.
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