Question 1

How is email verification API pricing different from email sending API pricing?

Accepted Answer

Sending APIs like SendGrid, Mailgun or Postmark charge for delivering a message — a flat rate or subscription tier per email you push out the door. Verification APIs like ZeroBounce, NeverBounce and Kickbox charge for a lookup — checking whether an address exists, accepts mail and is not a spam trap or disposable domain — before you ever send to it, and they bill in prepaid credits rather than per-send. The pricing shape is also different: verification vendors run steep tiered volume discounts, so the per-credit rate can drop three to four times between a small pack and a million-credit purchase, which matters far more here than in flat-rate sending because verification is usually a periodic bulk job (cleaning a list before a campaign) rather than a steady drip. Credit expiration is another gap sending APIs do not have — NeverBounce and Kickbox credits expire twelve months after purchase, while ZeroBounce credits never expire, which changes which vendor is actually cheaper if you buy in bulk but verify slowly.

Question 2

Why does the price per email drop so much at higher volumes?

Accepted Answer

Verification vendors sell prepaid credit packs, and like most bulk-purchase pricing the per-unit rate falls sharply as the pack size grows — a few cents per email at the smallest pack, down to a fraction of a cent at a million-plus credits. In this calculator's published-price brackets, ZeroBounce goes from roughly one cent per email at low volume to about a quarter of a cent past 750,000 credits; NeverBounce and Kickbox follow the same shape at slightly different rates. The practical effect is that verifying in one large batch is meaningfully cheaper per email than verifying the same total volume across several smaller top-ups, so if you know you need a few hundred thousand verifications this quarter, buying one pack sized for that volume beats buying four smaller ones as you go.

Question 3

Which email verification vendor is cheapest?

Accepted Answer

It depends entirely on your monthly volume, because the three vendors' tiered rates cross at different points rather than one being uniformly cheaper. At small list sizes the entry packs land within a fraction of a cent of each other. In the mid-range — tens of thousands to a few hundred thousand emails a month — ZeroBounce's published brackets are typically the cheapest of the three in this calculator's model. At very high volume the gap widens further because ZeroBounce's largest bracket rate is lower than Kickbox's. But list price is not the only variable: NeverBounce and Kickbox credits expire after twelve months while ZeroBounce credits do not, so a vendor that looks slightly pricier per email can still be the better deal if you buy in bulk once and draw down slowly. Enter your own monthly volume above to see which vendor wins at your scale.

Question 4

Do I need to verify my whole list every month?

Accepted Answer

No — verification is normally a periodic hygiene pass, not a per-send cost layered on top of every email you mail. The usual pattern is to verify new signups at capture (a small, steady trickle) and re-verify your full list or a stale segment before a big campaign, since email addresses decay over time as people abandon inboxes or domains expire. Skipping verification does not remove the cost, it just moves it: sending to a dirty list produces hard bounces, and every major ESP — SendGrid, Mailgun, Postmark among them — tracks your bounce rate and will throttle, warn or suspend a sending domain once it crosses roughly two to five percent, which can take down your entire sending reputation, not just the bad addresses. The verification spend modelled here is usually far smaller than the cost of a damaged sender reputation or a suspended ESP account, which is why it is normal to treat it as a recurring line item rather than a one-off.

電子メール検証 API コスト計算ツール

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よくある質問

検証の価格は送信の価格とどう違うのですか?

大量に送信するとメールあたりの価格が大幅に下がるのはなぜですか?

どこの業者が一番安いのでしょうか？

毎月リスト全体を確認する必要がありますか?