Can I cancel a verification once it has started?

The short answer depends on whether you mean a single email verification (one address through the dashboard widget or API) or a bulk task (a file of many addresses). Single verifications cannot be cancelled because they complete in seconds and there is no meaningful "in-progress" window to interrupt. Bulk verifications can be cancelled from the Valid Email Checker dashboard, and the engine refunds credits for any addresses that have not been processed yet.

Single verification: no cancel button by design

A single verification through the dashboard widget completes in 2 to 6 seconds for most addresses, up to about 15 seconds in the worst case where fallback kicks in. There is no UI button to cancel mid-flight because the request would finish before you could navigate to the cancel control. Closing the modal or refreshing the page does not stop the underlying call either — the edge function continues running until it returns a result, and the credit is consumed if a definitive answer comes back.

The one safety net: if the engine cannot deliver a definitive answer, the result comes back as Unknown and the credit auto-refunds. So even in the case where you wanted to cancel because the verification was taking too long, the worst case is Unknown with no credit cost. See what does unknown status mean.

Bulk verification: cancellable from the dashboard

Bulk tasks have a real "in-progress" state that can last from a few minutes to a few hours depending on list size. The dashboard surfaces a cancel control on tasks that are still processing. Clicking it stops the engine from sending more addresses to the provider, marks the task as cancelled, and triggers a credit refund for every address that had not yet been verified at the moment of cancellation.

Already-completed addresses keep their results. The credit cost for those is consumed — you paid for definitive answers and you got them. The refund only applies to the remaining unprocessed addresses, which the engine will not bill you for.

What cancelling a bulk task does behind the scenes

1. The task status flips from processing to cancelled. The dashboard immediately stops polling for new results.
2. The engine sends a stop signal to the verification provider. Any chunks that were already submitted to the provider may still complete (the provider does not always honour mid-flight cancels), but no new chunks are submitted.
3. For addresses that had no verification result, the engine issues a credit refund matching the unverified count. The refund appears in your Credits History within a few minutes.
4. For addresses that completed before cancellation, results are written normally to the verification-results table and the credits stay consumed.

The combination means you can confidently cancel a bulk that is going wrong (wrong list uploaded, second thoughts on which segment to verify) without losing the credits you paid for addresses already processed. See refunds and credit returns for the full refund matrix.

When you might want to cancel mid-bulk

• You uploaded the wrong file and noticed before too much processed. Cancel and re-upload the right one.
• You realised the list is bigger than you meant to verify in this pass. Cancel; split it; verify only the relevant segment.
• The list is producing a high Unknown rate, suggesting the underlying source has problems. Cancel and clean the source before re-uploading.
• You changed your mind about running this send entirely. Cancel; the refund returns the credits and you can use them elsewhere.

What happens if VEC itself goes down mid-task

Rare, but worth covering: if the engine has a system outage that interrupts a running bulk, the task is automatically marked failed and any unprocessed credits refund just like a manual cancel. You do not have to do anything special. The refund appears in Credits History tagged as a refund rather than a cancel, but the dollar effect is the same.