A: Thanks for the queries. Here are the answers to your questions:

1) Thread Limit:
The single email validation endpoint is designed for live/low-volume checks (e.g., website registration forms) with up to 5 parallel continuous connections. Temporary increases/bursts are acceptable. If you need to verify lists or large volumes at high speed, we recommend using the bulk verification API endpoint, which handles up to 50,000 emails per submission using our multi-server infrastructure. This bulk endpoint can verify about 1500 emails per minute on average. The bulk verification endpoint uses the power mode for verification. If you must use the single verification endpoint with a higher limit, please contact our support and let us know how you are planning to use our service. We will check if we can provide you any solution there.

2) Credits on "Unknown" / Connection Failures:
No, an "unknown" status does not consume any credits. Whenever an email returns as unknown, the credit is automatically refunded immediately. Similarly, requests that fail or return an API error do not consume credits.

3) Power Mode Timeout:
Because Power Mode performs deep individual inbox checks directly with the recipient's mail server, response times depend on the recipient server's responsiveness. We recommend setting a client-side timeout of at least 120 seconds. If a destination server is too slow, unresponsive, or busy to complete the check, the verification will resolve to "unknown" (and the credit will be auto-refunded).

Have a wonderful day ahead!