InboxPolicy vs MillionVerifier
By Aria Pramesi, founder of InboxPolicy · Updated July 4, 2026
MillionVerifier is the one-shot bulk-at-scale pick: $3.90/1k at entry, falling to $0.45/1k at 1M, with a free tier and aggressive unknown-resolution. InboxPolicy's 25,000-credit Growth pack has a lower unit price at $3.16/1k, but MillionVerifier's 10,000-credit entry purchase costs less overall; InboxPolicy costs $0.01 per fresh check but returns a send/hold/avoid decision with normalized signals for live agent workflows, keeping unknowns honest instead of guessing them safe.
What does each tool return: status fields or decisions?
MillionVerifier returns a status field per email, such as valid, invalid, catch-all, or unknown, built for bulk list cleaning.
InboxPolicy checks syntax, MX, and live SMTP against its own verification engine, then a deliverability policy turns that evidence into one of five actions: send, send_with_caution, review, retry_later, or avoid, along with a confidence score and normalized signals for catch-all, disposable, free, and role-account status.
When does MillionVerifier win?
MillionVerifier is the one-shot bulk-at-scale pick. It runs $3.90 per 1,000 at entry down to $0.45 per 1,000 at 1M, with a free tier and aggressive resolution of unknowns, so it is built to prune a static CSV before a send.
- Lower price at high volume (1M+: $0.45/1k); InboxPolicy's 25,000-credit Growth pack has a lower unit price, while MillionVerifier's 10,000-credit entry purchase costs less overall ($39 total at $3.90/1k).
- Free tier available.
- Resolves unknown or catch-all results into a keep or drop verdict rather than leaving them open.
If the job is cleaning 500,000 scraped rows once, MillionVerifier is the better fit.
When does InboxPolicy win?
InboxPolicy is built for agents deciding whether to send a specific email right now, not for bulk cleanup. It ships an MCP server exposing decide_send, verify_email, batch, and usage tools.
The REST API supports idempotency keys, per-item batch results, async batches up to 50,000 emails, and signed completion webhooks. Agents can also pay per call with no account or API key: a keyless request returns HTTP 402 with machine-readable payment requirements, the agent pays $0.01 USDC on Base via a PAYMENT-SIGNATURE header, and gets back a decision plus an on-chain settlement receipt.
How do InboxPolicy and MillionVerifier prices compare?
InboxPolicy charges $0.01 per fresh verification pay-per-call via x402, or through prepaid credit packs: Starter $5 for 1,000 credits ($5.00/1k), Builder $19 for 5,000 ($3.80/1k), Growth $79 for 25,000 ($3.16/1k). Volume pricing is available on request. There is no free tier, deliberately: free tiers attract list-cleaning abuse.
Two result types can cost 0 credits: cache re-verification within 72 hours (returns from_cache) and malformed-email rejection before SMTP.
MillionVerifier costs $3.90 per 1,000 at entry down to $0.45 per 1,000 at 1M. InboxPolicy's 25,000-credit Growth pack has a lower unit price at $3.16/1k, but MillionVerifier's 10,000-credit entry purchase costs less overall; at high volume, MillionVerifier wins on price. InboxPolicy's price is paying for a decision plus evidence and agent access, not just a lower per-row cost.
How does each tool handle unknown and catch-all addresses?
Background: our catch-all email verifier guide covers why these addresses cannot be confirmed by SMTP alone.
Roughly 30-40% of B2B addresses sit on catch-all domains, where a mail server accepts any address without confirming a real mailbox exists.
MillionVerifier resolves these unknowns aggressively, giving a binary keep or drop verdict, which is useful when a bulk sender just needs a prune decision. InboxPolicy maps unknown results to review. Catch-all results map to review by default or send_with_caution under aggressive strictness, rather than being silently marked safe.
| Feature | InboxPolicy | MillionVerifier |
|---|---|---|
| Price per check | $0.01/verification via x402, or $3.16-$5.00/1k prepaid packs | $3.90–0.45/1k |
| Output | Action (send, send_with_caution, review, retry_later, avoid) + confidence + normalized signals | Status field (valid, invalid, catch-all, unknown, etc.) |
| Free tier | None (eligible cache hits for the same normalized address and strictness within 72 hours when force_refresh is false, malformed rejection) | Yes |
| Unknown / catch-all handling | Unknown: review. Catch-all: review by default; send_with_caution under aggressive strictness | Resolved aggressively into keep/drop |
| Agent access | MCP server (decide_send, verify_email, batch, usage), keyless x402 pay-per-call | Dashboard/API only, no MCP, no x402 |
| Batch handling | Async batches to 50,000 emails, per-item results, signed webhooks | Bulk list upload |
| Best for | Real-time agent send-decisions | One-shot cleaning of large scraped lists |
Frequently asked questions
Is InboxPolicy more expensive than MillionVerifier?
Not across every tier. InboxPolicy charges $0.01 per fresh verification via x402, or $3.16-$5.00 per 1,000 through prepaid credit packs. MillionVerifier runs $3.90 per 1,000 at entry down to $0.45 per 1,000 at 1M. InboxPolicy's 25,000-credit Growth pack has a lower unit price at $3.16/1k, but MillionVerifier's 10,000-credit entry purchase costs less overall; MillionVerifier wins on price at high volume (1M+). InboxPolicy's price covers a send decision with normalized signals and agent-native access (MCP, x402), not just a status field.
Does MillionVerifier have a free tier and InboxPolicy doesn't?
Correct. MillionVerifier offers a free tier. InboxPolicy has no free tier, deliberately, since free tiers attract list-cleaning abuse. Two result types can cost 0 credits: eligible cache hits for the same normalized address and strictness within 72 hours when force_refresh is false can return from_cache, and malformed emails are rejected before SMTP.
Which tool is better for cleaning a large scraped list?
MillionVerifier. It runs $3.90 per 1,000 at entry down to $0.45 per 1,000 at 1M, with a free tier and aggressive unknown resolution, so it is built for one-shot bulk cleaning of large lists at scale. InboxPolicy Growth is $79 for 25,000 ($3.16/1k), while MillionVerifier's entry is $39 for 10,000 ($3.90/1k), a lower total purchase. InboxPolicy is priced and built for a different job: per-email send decisions inside live agent workflows, not bulk list pruning.
Which tool is better for AI agents deciding whether to send an email?
InboxPolicy. It ships an MCP server exposing decide_send, verify_email, batch, and usage tools, plus a keyless x402 flow where an agent receives an HTTP 402 with payment requirements, pays $0.01 USDC on Base via PAYMENT-SIGNATURE, and gets back a decision and on-chain settlement receipt. MillionVerifier has no MCP or x402 support.
How do the two tools handle catch-all or unknown email addresses?
Roughly 30-40% of B2B addresses sit on catch-all domains. MillionVerifier resolves unknowns aggressively to give a binary keep/drop verdict. InboxPolicy maps unknown results to review. Catch-all results map to review by default or send_with_caution under aggressive strictness, rather than being silently marked safe, on the reasoning that a wrong guess costs more in a send-decision system than an unresolved row in a list.
How accurate is InboxPolicy compared to status-field verifiers like MillionVerifier?
InboxPolicy's prior verification engine showed roughly 90% typical valid-verdict agreement with MillionVerifier across more than 2 million verifications, though agreement varies by vertical and drops as low as 60% in some. This is a rough baseline, not a formal recent benchmark, and both tools' accuracy depends heavily on list source and industry.