Should I verify imported lead emails?
When to verify imported lead emails and what to choose.
Yes — verify before you send. CSV uploads are free (no credits). The import screen has an Automatically verify lead emails on upload checkbox, but it is off by default. Turn it on for risky lists, or verify the CSV with an external tool before uploading. If a big chunk are invalid, they bounce — and bounces over 3–5% damage your sender reputation across every campaign on that inbox.
Why verification matters more than people think
- A 20% bounce rate can pause your campaign automatically (bounce protection kicks in)
- Even if it doesn't pause, Gmail flags the sending domain — future campaigns from the same inbox land in spam
- Recovering from a damaged reputation takes weeks of careful warmup
Verification tools worth using
- NeverBounce, ZeroBounce, MillionVerifier — dedicated email verification services, usually 1–3 cents per email
- Apollo and Clay — lead sources with built-in verification (mostly good, still worth spot-checking)
- Instantly and similar cold email platforms — verification built in before send
What "verified" actually means
A verified email passes three checks:
- Syntax — the address is formatted correctly
- Domain — the domain exists and has working mail servers
- Mailbox — the specific inbox accepts mail (not always checkable, but the better tools try)
If you can't verify beforehand
Run a small CSV sample only as a bounce-risk spot check, not as a campaign performance test. If bounce rate stays under 3% on that sample, the list is probably clean enough. Above 3%, verify the rest before continuing. For campaign learning, use the larger test sizes in Best Practices.