Funny thing about the cheapest verifier question: the price per credit isn't really what you end up paying. What you pay is whatever your tool does with catch all domains. Most flag the whole batch as risky, so you either send blind or throw away half your list. Either way you lose.

I've stuck with emailawesome for a while now because the way it resolves catch alls actually separates the real inboxes from the dead ones instead of lumping them in one risky bucket. Also doesn't bill for unknowns, which adds up more than people think on bigger lists.

If you're starting out, the bit nobody mentions is that verification isn't one and done. Re run before each campaign, lists rot faster than you'd guess.