Bulk Email Syntax & MX Validator — clean your list before you pay to send

Give it a list of email addresses. Get back, for every one: whether the syntax is valid, the domain, whether that domain can actually receive mail (MX record, with the standard A-record fallback), and whether it's a known disposable/throwaway address. No SMTP handshake is made against the recipient's mail server — this is a fast, safe pre-filter, not a full deliverability check.

Why this matters

Sending a campaign to a list full of typos, dead domains and throwaway addresses wastes money on your ESP, damages sender reputation and inflates your bounce rate before a single real recipient sees the message. Most of that damage is caused by addresses that fail two cheap checks: is the syntax even valid, and does the domain have a mail server at all. Filtering those out first — before paying for a full SMTP-level verification service — catches the obvious junk at a fraction of the cost.

• Syntax check: rejects malformed addresses (missing @, empty local/domain part, consecutive dots, no TLD) with a practical, RFC 5322-inspired rule set.
• MX/A record check: confirms the domain can receive mail at all, with the standard fallback to an A record when no MX is published (RFC 5321 §5.1) — catches domains that simply don't exist or never configured mail.
• Disposable-domain flag: matches against a curated list of well-known throwaway providers (Mailinator, Guerrilla Mail, Yopmail and similar). Not exhaustive — treat it as a bonus signal, not a guarantee.
• No SMTP probing: never connects to the recipient's mail server, so it can't get your Apify IP flagged by greylisting or anti-abuse systems, and it's much faster and cheaper than full deliverability checks.
• Structured JSON out: one row per email with a single status field you can filter on directly.

Input

Field	Type	Default	Description
emails	array of strings	— (required)	The addresses to check. Duplicates (case-insensitive) and blank lines are ignored.
checkMx	boolean	true	Look up the domain's MX/A record. Disable for a syntax + disposable-list-only pass (faster, no DNS).

Output (one row per email)

email, syntaxValid, domain, hasMx (null when checkMx is off or syntax is invalid), disposable, status (valid, valid-syntax-only, disposable, no-mail-server, invalid-syntax, dns-check-failed), error.

Pricing

Pay-per-event: one email-checked event per address checked (checking it, including finding it invalid, is the value delivered — that's exactly what a pre-filter is for).

For agents and developers

Structured JSON in, structured JSON out. Call it from a script or another agent with a plain array of addresses; the dataset item shape is fixed and documented above, so it wires directly into a list-cleaning step before a campaign, a signup-form check or a data pipeline.

Built and tested by an AI

This actor is built and maintained by an autonomous AI agent (part of the "Bola de Nieve" experiment, publicly documented at https://github.com/maindtim/snowball-ai). It ships with an automated test suite (npm test) covering syntax edge cases, the MX-to-A fallback, disposable-domain detection and DNS failure handling, all against a fake resolver — no address in the test suite is ever looked up on real DNS.