One API call. A strict yes/no answer with a reason code. Uncertain mailboxes count as “no”, so bad addresses never reach your sender reputation.
curl -X POST https://www.mailrambo.com/v1/verify \
-H "Authorization: Bearer mr_live_..." \
-H "Content-Type: application/json" \
-d '{"email": "jane@acme.com"}'const res = await fetch("https://www.mailrambo.com/v1/verify", {
method: "POST",
headers: {
Authorization: `Bearer ${process.env.MAILRAMBO_KEY}`,
"Content-Type": "application/json",
},
body: JSON.stringify({ email: "jane@acme.com" }),
});
const { deliverable, reason } = await res.json();import os, requests
r = requests.post(
"https://www.mailrambo.com/v1/verify",
headers={"Authorization": f"Bearer {os.environ['MAILRAMBO_KEY']}"},
json={"email": "jane@acme.com"},
)
print(r.json()["deliverable"], r.json()["reason"]){
"email": "jane@acme.com",
"deliverable": true,
"reason": "mailbox_exists"
}Call it from your code, drop it into your signup flow, or run full lists through the dashboard.
A REST API with single and batch endpoints, machine-readable reason codes, and fail-closed answers you can branch on without guesswork.
Stop fake and disposable signups at the door, protect your transactional email sending, and keep your CRM free of dead addresses.
Clean client lists in bulk, grade every lead A–F, and get gatekeeper profiles and playbooks before a campaign goes out.
No SDK required. Any HTTP client works.
Sign up free and create an API key from the dashboard. Keys are shown once, stored hashed, and revocable anytime.
Send one address, or up to 200 with /v1/verify/batch and poll for results. A full check costs 1 credit; add ?mode=fast for a free, sub-second check on signup forms.
deliverable is true only for confirmed mailboxes. The reason code tells you why: disposable, catch_all, mailbox_not_found and more.
npm install mailrambo · pip install mailrambo
For Better Auth email/password signup, use the MailRambo plugin and setup guide.
Coming soon to ChatGPT: check addresses and your credits from a ChatGPT conversation with your MailRambo account. How it works.
Full API reference →Check the address when the user submits the form - free and in well under a second with fast mode. Reject what won't receive mail, before it becomes a fake account, a bounced welcome email, or a dead CRM record.
jane@gmial.com comes back with “Did you mean jane@gmail.com?”, and domains with no mail server are rejected.Using Better Auth? Add MailRambo's signup-screening plugin →
async function onSignup(email) {
const r = await fetch("/api/check-email", {
method: "POST",
body: JSON.stringify({ email }),
});
const { deliverable, reason, suggestion } = await r.json();
if (deliverable === false) {
// "possible_typo", "disposable", "no_mx", ...
return showError(messages[reason], suggestion);
}
return createAccount(email);
}Whether it's a signup form, a CRM or a campaign list, dead addresses cost you long before you notice.
Typos, throwaway inboxes and abandoned accounts pile up. Every send to a dead address wastes money and chips away at your sender reputation.
Cross a few percent bounce rate and Gmail, Outlook and corporate filters start distrusting your domain - including your password resets and receipts.
Most validators return “risky” or “unknown” and leave the decision to you. MailRambo is fail-closed: only confirmed mailboxes are deliverable.
Most email validators are glorified ping tools. We built something fundamentally different.
While other tools return a green checkmark, MailRambo returns an intelligence briefing.
Under the hood, this runs in milliseconds.
↓ Now see what your dashboard actually looks like ↓
Upload a list in the dashboard and get far more than valid/invalid - the intelligence that wins and keeps clients.
A client hands you a 5,000-email list and wants the campaign live tomorrow.
Bulk upload → dead and risky addresses flagged → removed before sending → the client's domain stays clean.
200 leads from a conference. Who should sales call first?
A–F grades, gatekeeper profiles and corporate DNA so SDRs hit the highest-value, verified leads first.
A prospect asks why their emails land in spam.
SPF, DKIM, DMARC, BIMI and PTR checks turned into a technical audit you can present as a consulting deliverable.
MailRambo doesn't just score - it tells you exactly what to do with each lead.
1 credit = 1 verified address, shared between the API and the dashboard. Upgrade, downgrade or cancel anytime.
Need credits without a subscription? Pay-as-you-go packs from $9 for 2,000 checks - never expire.
Compare plans →100 free verifications every month. No credit card required.