Email verification means - check if an email address exists or not without sending an email. This is useful if you manage large email marketing lists of consumer email addresses -- if a bunch of emails you send hard bounce, then you'll be blocked by your ESP. Email verification is a way to avoid that.
The companies below provide UIs and APIs for verifying emails. Costs are usually in the cents-per-email range, so they're very affordable.
They offer bulk (list) verification for verifying a whole list, and also a real-time verification API for verifying email at the point of capture. The API will also detect disposable email addresses, and suggest spelling corrections if it thinks the user made a typo (eg gmial instead of gmail). I like them because they have a strict no-spammer customer policy, so their results are usually very good.
Owned by Zoominfo (an email guessing sales tool), they offer bulk verification and real time verification.
They also offer list verification and API verification.
Briteverify used to be the 'best' offering, but now they're part of the validity suite, which is a whole bunch of email and sales tools bundled together.
The tools below provide email verification as a self-hosted solution, but due to the nature of how SMTP reputation works, they're probably not going to be super accurate unless you already have warm IPs. Plus many email providers just accept all emails without asking questions as an anti-spam measure, so your milage may vary.
- email-verifier (go) - https://github.com/AfterShip/email-verifier
- check-if-email-exists - https://github.com/reacherhq/check-if-email-exists
- email-exists - https://github.com/MarkTiedemann/email-exists
Site logo from Juicy Fish