Email bounce rate, explained

Bounce rate = (bounced emails ÷ emails sent) × 100. If you send 10,000 messages and 220 bounce, your bounce rate is 2.2%.

What counts as healthy

• Under 0.5% — excellent, typical of verified double opt-in lists.
• 0.5%–2% — acceptable for most senders.
• 2%–5% — warning zone; mailbox providers start throttling.
• Above 5% — ESPs may suspend your account and inbox placement collapses.

Hard and soft bounces should be tracked separately: a 3% rate that is mostly soft bounces from one outage is very different from 3% of non-existent mailboxes.

Why bounce rate climbs

• Lists aged more than 90 days without re-verification (B2B lists decay roughly 2% per month as people change jobs)
• Unverified signup forms letting typos through
• Purchased or scraped lists
• Re-mailing addresses that already hard bounced
• Importing an old CRM export wholesale

Bringing it back down

• Verify the entire list before your next send and remove invalids.
• Permanently suppress every historical hard bounce.
• Add point-of-capture verification so new typos never enter.
• Segment out catch-all addresses and warm them separately.
• Sunset unengaged contacts after 6–12 months.
• Re-verify quarterly, or before any large campaign.

A 50,000-address list at 6% bounce is 3,000 damaging sends. Verifying it first typically costs less than the reputation recovery afterwards.

Measuring it properly

Use your ESP's bounce classification rather than counting all failures together, and compare against the numbers in the deliverability benchmarks. Clean a list now with the bulk email checker.