ZapBounce and Apollo
Apollo provides both the data and the sending, and it labels addresses in its database as verified or guessed. That label is genuinely useful and it is doing something different from a live check.
Apollo's verified status usually reflects its own database evidence and past validation. It is a statement about their records rather than about the state of the mailbox this morning.
A database label ages; a mailbox changes
An address marked verified in Apollo's database was verified at some point. People change jobs at around a quarter of a B2B list per year, and the label does not decay in step with them.
Guessed addresses are the larger problem. Apollo is honest in labeling them, and they were produced by applying a company's pattern to a name, which is a guess even when it is a good one.
Those guesses cluster on corporate domains, which is where accept-all servers are common, so a live check often cannot confirm them either. Knowing that is better than assuming the pattern held.
How the data moves
Export from Apollo with the confidence label intact
The verified-or-guessed distinction is what tells you which addresses need the live check most.
Verify the guessed addresses first
That is where the bounces concentrate, and checking them alone keeps the spend proportionate.
Re-check verified addresses on age
Anything Apollo last touched more than a few months ago is worth a live handshake before a sequence.
Compare the two labels in your results
The invalid rate on guessed versus verified is a number worth having, because it tells you how much to trust the label in future.
Setting it up
- Export the Apollo list including the email confidence label.
- Split into verified and guessed before checking anything.
- Verify the guessed addresses first and measure the invalid rate.
- Verify the verified ones too, and compare the two rates.
- Sequence only addresses that passed a live check, whatever Apollo's label said.
- Route catch-all and unknown addresses to a calling or LinkedIn play instead.
Apollo: common questions
Is Apollo's verified label reliable?
It reflects their database evidence at some point in the past. A live handshake tells you about the mailbox now, and the two answer different questions.
Should I verify the guessed addresses or drop them?
Verify them. A good share of pattern guesses are correct, and dropping them discards real prospects.
Why do guessed addresses come back catch-all so often?
Because they cluster on corporate domains, and corporate domains commonly run accept-all servers to defeat harvesting.
Check a Apollo export today
100 free checks a month, no card. Unknown results and duplicates are never billed.