What are Verifalia's Standard, High and Extreme quality levels?

Verifalia sells one credit pack and lets you choose, per job, how much effort each address gets. The choice is called the result quality level. You pick Standard, High or Extreme when you submit the list, and the level multiplies the credits each address uses.

Here's the full model as Verifalia's help pages state it, read on 24 September 2026. Standard uses 1 credit, 1 validation pass and waits 5 seconds against a tarpit. High uses 2 credits, 3 passes and a 50-second wait. Extreme uses 4 credits, 9 passes and a 2-minute wait. Verifalia's credit packs never expire, and its free plan gives 25 checks a day.

A tarpit is a mail server that answers slowly on purpose to wear out bulk senders. A short wait gives up early and returns an unknown result. A longer wait sits it out and gets a real answer. The extra passes do a similar job for greylisting servers, which refuse the first try and accept a later one.

So the higher levels buy fewer undecided rows, at two or four times the credits. Whether that pays depends on your list. A list whose domains answer on the first try gains little. A B2B list full of Microsoft 365 domains, which rate-limit verification traffic hard, is where extra passes earn their cost. Verifalia's pricing page showed placeholder marks instead of prices when read, so we quote no Verifalia price here.

ZapBounce takes the other route to the same problem: one check type, one price per answer. A row where the server gives no usable answer comes back as unknown, with its reason attached (greylisted, throttled, probe_blocked or timeout). Unknown is never billed, so you never pay for effort that found nothing. Checks cost $5 for 1,000 on the pricing page, and how verification works shows each step.