Check if email is available or not in bulk

Hello
I have bulk list of emails: Hotmail,yahoo,gmail that I want to check if the username is available or not
is there a tool that can do that?

I'm a Banana said:

Hello
I have bulk list of emails: Hotmail,yahoo,gmail that I want to check if the username is available or not
is there a tool that can do that?

Click to expand...

Check email verifiers online
Tons of them
Although mostly paid now

medialounge said:

Check email verifiers online
Tons of them
Although mostly paid now

Click to expand...

I tested some but even when they say the email bounce it's not always means the email is available to register

Email verifiers check if an address exists and can receive mail — but they won't tell you if a username is available to register. Those are two different things.


For Hotmail and Gmail specifically, the only reliable way to check username availability is to attempt account creation directly. No third party tool can query that in bulk without hitting rate limits or getting blocked.


If you're trying to register accounts at scale, the bottleneck isn't the checker — it's the phone verification requirement on new accounts.

You can use tools like ZeroBounce, NeverBounce or Bouncer. They won’t check “availability” directly, but they’ll tell you if the emails are valid or not.

You can check with ZeroBounce, NeverBounce, or Bouncer.

The previous answer is correct on the distinction. To add the technical specifics:
Hotmail/Outlook has a username availability check that fires as an AJAX call during signup when you type in the field. That endpoint is directly queryable, but Microsoft rate-limits it at the IP level after roughly 10-15 requests. At bulk scale, you'd need per-request residential IP rotation just for the availability check phase before touching registration.
Gmail uses a similar lookup but Google's signup flow also runs JS fingerprinting and behavioral analysis on the page. A raw requests approach won't get clean results — you need a headless browser with proper rendering and user behavior simulation to even get consistent responses from the availability check.
Practically: the checker is the easy part. As the last reply said, the real wall is phone verification at registration. One carrier number per account, no way around it at scale. Most bulk email registration projects hit this limit and stall there, not at the username check.

they often get rate-limited or blocked pretty quickly, if you're serious, look into a paid service that handles the verification at scale. they'll have better infrastructure to deal with the rate limits and security measures

Services like ZeroBounce, NeverBounce, Bouncer do not perform any real checking so they will not even detect catch-all domains