What is the maximum number of emails in one bulk job?

A single bulk verification task in Valid Email Checker accepts up to 1,000,000 unique email addresses. That is the hard cap baked into the upload form. Past the cap, the form refuses to start the task and shows the message "Maximum 1,000,000 emails allowed per upload. Please split your file into smaller parts."

How the count is measured

The email count is measured after the file is parsed and after duplicate removal runs (if you left the Remove Duplicates option on, which is the default). So if you upload a CSV with 1.2 million rows but 250,000 of them are duplicates, the unique count is 950,000 and the task proceeds normally. If the deduplicated count still exceeds 1,000,000, the cap kicks in. The file size cap of 100 MB is a separate check and applies in parallel to this one.

1. You upload or paste your list.
2. The parser extracts valid-looking email addresses and counts them.
3. If Remove Duplicates is on, identical addresses collapse to one (case-insensitive).
4. The deduplicated count is compared against the 1,000,000 cap.
5. On a pass, the credit check runs against your balance. On a fail, the upload is blocked with the cap message.

Why the limit is set here

A million addresses is the size at which chunked processing, parallel verification across multiple servers, and the result download path all stay reliable for every customer. Past this point, individual tasks would block infrastructure capacity that other users rely on. We picked the cap to keep large jobs working without starving small ones.

Working with lists above 1M

If your list is genuinely larger than 1,000,000 addresses, split it into chunks and upload each as a separate task. The Uploads & Results page handles any number of tasks per account, so a 4-million-address list across four 1-million-address tasks is fully supported. Many large customers run their full database this way on a quarterly cadence.