Built-in verification checks whether an address exists (syntax, MX, SMTP handshake, catch-all detection) before a campaign sends to it. Buyers care because bounces damage sender reputation: Instantly's own guidance for AI campaigns is to keep bounces "at or below 1 percent" (Instantly blog, Nov 2025), and mailbox providers punish higher rates (see Google and Yahoo sender rules and Reputation and blocklists).
Verification used to be a separate purchase from NeverBounce or ZeroBounce (Email verification). In 2026 it is part of the sequencer and the price is falling toward zero.
How it works
On upload or reveal, the tool runs each address through checks: syntax, domain MX records, an SMTP probe without sending, and catch-all detection (domains that accept everything, which can't be proven valid). Results tag each lead as valid, invalid, risky or catch-all, and the campaign skips the bad ones. Some tools re-verify at send time; some only verify database reveals.
Who does it well
| Player | Verification (as of Oct 2026) |
|---|---|
| Woodpecker | "Unlimited email verification (including catch-all)" on every plan (pricing) |
| Smartlead | Included quota: 2,000 (Base) to 170,000 (Unlimited Prime) verifications/mo; packs from $32 up to 960,000 credits (pricing, pricing.md) |
| Saleshandy | 500 one-time credits on Starter; included in Lead Finder credits on Pro/Scale (pricing) |
| Salesforge | 1,000 validation credits/mo on Growth (pricing) |
| lemlist | "Email finder & verifier" on all plans, credit-consuming (pricing; MCP docs) |
| Instantly | Credits: 0.25 credit per lead verification per a third-party breakdown; API endpoint "Create email verification" (docs index) |
| Reply.io | Paid add-on from $20/mo (5,000–300,000 validations); included on AI SDR and Agency (pricing) |
| PlusVibe | "Limited" on Personal, full on Business (pricing) |
| EmailBison | Not documented; its EmailGuard integration is inbox-placement testing, not list verification |
Where implementations differ
- Price. From unlimited and free (Woodpecker) to metered credits (Instantly, Reply.io add-on). At Instantly the same credit pool pays for leads and AI replies.
- Catch-all handling. Woodpecker explicitly includes catch-all verification. Most vendors return "risky" and leave the decision to the user. Catch-all-heavy B2B lists are where cheap verification stops being useful.
- When it runs. Reveal-time verification inside a Built-in lead database is now standard; re-verification of uploaded lists before each send is not.
- Programmatic access. Instantly exposes verification as an API endpoint; lemlist exposes it as an MCP tool. An agent can now verify before enrolling without a human.
No vendor publishes verification accuracy or false-positive rates for catch-all domains. Head-to-head accuracy could not be compared in this pass.
Risks and abuse
SMTP probing at scale gets the probing IPs blocklisted by receiving servers, so vendors route it through dedicated infrastructure or third-party APIs. Verification also creates a false sense of safety: a "valid" address can still be a spam trap or a role inbox that complains. And verification does not make a recipient lawful to contact under GDPR and ePrivacy.
What this means for an entrant
- Include verification free, with catch-all detection, on every plan. Woodpecker already does; charging for it is a losing position.
- Buy it wholesale from a Email verification vendor rather than run SMTP probes yourself — the infrastructure and IP reputation cost is not worth it at launch.
- Verify automatically at enrolment, not just at upload, and block sends to invalids by default. This is a Bounce protection feature as much as a verification one.
- Expose it to agents (API and MCP) so AI-built campaigns cannot skip it.