An enriched list is not the same as a sendable list. Enrichment finds an email address; validation confirms that address will actually accept mail rather than bouncing and damaging your sender reputation on contact number one.
The Validation Pass
Every single email in a list, with zero exceptions, is run through ZeroBounce before it is cleared to enter a sequence. ZeroBounce checks mailbox existence, catch-all status, spam trap risk, and general deliverability signals, returning a clear status for each address.
How Addresses Are Categorized
- Valid: confirmed deliverable, cleared for immediate sequencing
- Invalid: confirmed non-existent or dead, removed from the list entirely
- Catch-all: the domain accepts all mail regardless of whether the specific address exists, labeled with a send-risk flag rather than excluded outright
- Risky or unknown: addresses with ambiguous signals, held back or sent only in small monitored batches rather than a full sequence push
Why Catch-All Addresses Need Special Handling
Catch-all domains will accept an email sent to almost any address at that domain, valid or not, which means a “successful send” is not proof the person actually received it. We do not exclude catch-all addresses outright, since many legitimate contacts sit on catch-all domains, but we flag them so sending volume and expectations can be adjusted accordingly.
Impact on Deliverability
Lists that skip this step typically see 8 to 15% bounce rates, which is enough to trigger spam filter attention within the first few hundred sends. Validated lists we deliver typically run under 2% bounce rate, keeping sender reputation clean for the life of the campaign.