Bounces hurt more than a single failed send — they drag down your sender reputation and put your whole domain at risk. Two sources of avoidable bounces were hitting harder than they should: leads pulled in by the AI harvester, and addresses that had already bounced once but kept getting emailed again.
What was happening
Contacts sourced by the AI lead harvester were trusted on the source's own "validated" flag — a label that often meant little in practice. That flag can mean an address merely looked plausible, not that a mail server would actually accept it, so we were effectively taking the source's word for it. We were not running our own deliverability check before adding them to your list, so addresses that were syntactically broken, on disposable throwaway domains, or simply not deliverable went straight into campaigns and bounced at a high rate. You would only find out they were bad after the bounce had already landed against your sending reputation. Separately, when an address bounced, nothing stopped it from being imported again later and emailed a second time, so the same bad contact could bounce over and over across different imports. Worse, some bounces are not about one mailbox at all: a mail-routing loop fails for the entire receiving domain, so every address you had at that domain would keep bouncing too, multiplying the damage from a single misconfigured destination.
What we fixed
Harvested contacts are now verified for real deliverability at import. Before an address is trusted, it passes a free syntax and disposable-domain pre-filter — which catches the obviously bad ones at no cost — and then a genuine MX/SMTP check that confirms a mail server is actually there to receive it, rather than relying on the source's "validated" claim. Addresses that cannot actually receive mail are caught before they ever enter a campaign. On the suppression side, any address that bounces is now added to your suppression list, so it will not be re-imported and emailed again. And for mail-routing-loop bounces — the kind that fail for the whole receiving domain rather than a single inbox — we suppress the entire recipient domain, so its sibling addresses stop bouncing as well.
Why it matters
Fewer bounces means a healthier sender reputation, which means more of your email reaching the inbox. Mailbox providers watch your bounce rate closely, and a run of bad sends can push your legitimate mail to spam — so every bounce you avoid protects the contacts you actually care about. Verifying harvested leads at the door keeps junk addresses out of your campaigns instead of letting you discover them the hard way, after the damage is done. Suppressing bounced addresses — and whole looping domains — means you stop re-sending to recipients that have already proven they cannot be reached. The net effect is cleaner lists, lower bounce rates, and less drag on the deliverability of the contacts that do matter.