40% fewer bounces. Same ESP. No tricks.

A client came to us last year with a problem their ESP couldn't solve. Their bounce rate was hovering around 6%, well above the 2% threshold where email providers start raising eyebrows. Their deliverability team had tried everything on the platform side — authentication checks, sending limits, IP warming. Nothing moved the needle.

The issue wasn't their ESP. It was their data. We ran a hygiene audit on their 120,000-contact database and found the usual suspects: 18% of records had invalid or deactivated email addresses, 12% were duplicates across different lists, and 8% had formatting issues that caused silent bounces (emails that looked right but didn't resolve).

They didn't need a better email platform. They needed cleaner data going into the one they had. We ran a full deduplication and verification pass, suppressed the hard bounces, normalized the formatting, and set up a quarterly refresh cadence. Within one quarter, their bounce rate dropped from 6.1% to 3.6% — a 40% reduction.

But the downstream effects were bigger than the bounce number. Their open rates climbed from 18% to 24% because emails were actually landing in inboxes. Their domain reputation score improved. Their ESP stopped throttling their sends. The marketing team stopped getting angry emails from sales about campaigns that never arrived.

The most overlooked part of this story is the ongoing maintenance. A one-time cleanup is useful but temporary. What kept the bounce rate down was the quarterly refresh — a smaller, faster pass that catches new decay before it accumulates. Think of it like changing your oil instead of waiting for the engine to seize.

If your bounce rate is above 3% and you've already exhausted your ESP's tools, the problem is probably not deliverability. It's data hygiene. Fix the data and the deliverability usually fixes itself.