Relaybase checks whether an email address is real before you hit send, so your campaigns land in inboxes instead of bouncing back. No technical setup required.
No credit card required · Upload a spreadsheet in 30 seconds
Your list, checked
jane@company.com
Safe to send
info@old-domain.co
Risky, may bounce
jhon@gmial.com
Invalid, typo detected
2,481 addresses checked
312 bounces avoided
Dead emails, typos, and disposable addresses silently destroy your deliverability. When bounce rates climb, ESPs throttle you, domains get blacklisted, and real customers never see your emails.
~10%
inbox delivery lost for
every 1% bounce rate increase
You don't need to be technical to use it. Upload a spreadsheet, or let your developers plug in the API.
Campaigns bouncing and hurting your sender score
Clean your list before every send and keep landing in the inbox.
Prospect lists full of dead or mistyped addresses
Verify leads on import so reps only work contactable people.
Customers typing the wrong email at signup or checkout
Catch typos in real time so receipts and resets actually arrive.
Rolling your own validation and maintaining blocklists
One API call returns a clear verdict, with SDKs and webhooks.
Four checks, done in under a second per address.
Typos and malformed addresses are caught right away. Think "jhon@gmial.com" instead of "john@gmail.com".
We confirm the company or provider behind the address actually runs an email server that can receive mail.
Relaybase asks the mail server whether that specific mailbox exists, without ever sending the person an email.
Every address comes back as Safe, Risky or Invalid, with a plain-English reason and what to do next.
Five layers of checking, explained in plain English, with the technical name underneath for your dev team.
Misspelled addresses like "gmial.com" are flagged straight away with no waiting, and it doesn't count against your quota.
Syntax & format validation
We confirm the company or provider behind the address actually runs a mail server.
MX record lookup
We politely ask the mail server whether the mailbox is real, without sending anything to the person.
Live SMTP probe
Temporary signup emails people use to grab a freebie are flagged so they don't pollute your list.
Disposable domain detection
Some domains say yes to every address. We label those as risky so you can decide how to treat them.
Catch-all detection
Drop in a CSV of thousands of contacts and download a clean list. Or use the API if you prefer.
Bulk CSV & API
You don't really care whether an MX record exists. You care whether this send will bounce, whether your reputation will hold, and whether your provider will keep letting you send. That's the decision we make for you.
Know an address is real before it ever enters your send queue.
A confidence score on every address, not just a binary verdict.
Domain and sender intelligence that warns you before providers do.
Keep known-bad addresses out of every future campaign, automatically.
One API call. Works with any language, any stack. No spreadsheet needed.
curl -X POST https://api.tryrelaybase.com/v1/email/single-validate \
-H "Accept: application/json" \
-H "Content-Type: application/json" \
-H "X-RB-Key: rb_key_..." \
-d '{"email": "jane@company.com"}'SDKs for Go, Node, Python
OpenAPI spec available
Webhook support for async bulk jobs
Rate limiting built in
Start free. Upgrade when you need more.
Free plan available. No credit card required. Set up in 5 minutes.
Get started free
Email validation that protects your sender reputation.