Hard Bounce Rate Impact Calculator

Hard Bounce Thresholds

• Under 0.5%: Excellent. Indicates clean, well-maintained list.
• 0.5–1%: Acceptable. Schedule validation within 30 days.
• 1–2%: Elevated. Run list validation before next large send.
• Above 2%: Critical. Immediate action required to prevent blacklisting.

ISPs track hard bounce rates at the domain and IP level. Sustained rates above 2% trigger spam filter adjustments that affect all emails from that sending infrastructure, including to clean addresses.

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