The number of email verifications you can perform depends on your monthly verifications quota (click on your name in the upper-right corner of your dashboard to see how many verification requests you have left).
There is also a limit per domain depending on your subscription:
1) You can verify up to 200 email addresses from a specific domain name every 24 hours on the Free, Starter, and Growth plans.
2) You can verify up to 500 email addresses from a specific domain name every 24 hours on the Business, and Enterprise plans.
In the Bulk Email Verification, each bulk is limited to 10,000 emails maximum.