How to verify an email address
Updated September 3, 2026
Verifying an email address means proving, without sending a campaign, that mail to that address can actually be delivered. There are five layers of proof, from cheap and instant to slow and definitive. This guide walks through each of them, in the order you should run them.
Step 1 — Check the syntax against the RFC rules
Most invalid addresses fail here: a missing @, two dots in a row, a space, a trailing dot, an over-long local part, or quoting that no mail server will accept. An RFC-strict syntax check costs nothing and removes typos and broken imports instantly.
Paste any address into the free validator and the syntax verdict is the first thing you see, along with the exact rule that failed.
Step 2 — Confirm the top-level domain really exists
Addresses ending in .con, .cmo, .gmial or an invented TLD are common in hand-typed lists. Checking the domain suffix against the IANA registry of real top-level domains catches them before you waste any budget.
Step 3 — Look up DNS and MX records for the domain
A domain can only receive mail if it publishes MX records (or a usable A record fallback). If the domain does not resolve at all, has no mail host, or publishes a null MX record — a single "." entry meaning "this domain accepts no mail" — the address is guaranteed to bounce.
This step also reveals who actually hosts the mailbox: Google Workspace, Microsoft 365, Yahoo, Zoho, Proton, Amazon SES and so on, which is useful for segmentation and for knowing how strict the receiving server will be.
Step 4 — Screen for disposable domains and role accounts
Temporary and burner mailboxes technically accept mail, but they expire, never engage and sometimes turn into spam traps. Role accounts such as info@, sales@, support@ and noreply@ go to a shared inbox rather than a person and drag engagement down.
Both are matched instantly: disposable domains against a bundled list of thousands of known providers, role accounts against the standard local-part patterns.
Step 5 — Run an SMTP check when you need certainty
Only the receiving mail server knows whether one specific mailbox exists. An SMTP-level verification opens a conversation with that server and asks — without delivering a message. This is the only way to separate a live mailbox from a dead one on a valid domain.
Because it costs money per address, always run steps 1–4 first for free, then spend credits only on the addresses that survive.
How to verify a whole list at once
Paste thousands of addresses separated by commas, spaces or new lines, or import a CSV — the column containing emails is detected automatically and duplicates are removed. Results stream in progressively and everything is exportable as CSV, grouped by mailbox provider, business versus free mailbox, or company category.
Try it on your own list
Run the free validator on any address or CSV, then spend credits only on the addresses that survive.
Frequently asked questions
Keep reading
- Email validation vs email verification
Validation checks whether an address could receive mail; verification confirms the mailbox exists. Learn what each one catches, what it costs and when to use both.
- How to clean an email list
A practical checklist for cleaning an email list: dedupe, fix typos, drop dead domains, remove disposables and role accounts, then verify the survivors before you send.
- Why do emails bounce?
The real causes of hard and soft email bounces, what each bounce code means for your sender reputation, and how to cut your bounce rate before the next send.