How fast is bulk email verification?

Most lists move faster than people expect. Approximate processing times:

• 100 emails — seconds
• 1,000 emails — under a minute
• 10,000 emails — 5 to 10 minutes
• 100,000 emails — 15 to 30 minutes
• 1,000,000 emails — 1 to 2 hours

What controls the actual speed

Two things, mainly:

• The mix of mail providers in your list. Gmail, Outlook, and Yahoo answer SMTP probes fast. Some corporate mail servers and smaller providers are slower or rate-limit our probes, which adds wait time.
• How many addresses share a domain. We respect per-domain rate limits to avoid getting our verification IPs blocked. A list of 10,000 addresses spread across 5,000 domains runs faster than the same 10,000 all on the same corporate domain.

We use multiple verification servers around the world and run verifications in parallel across many connections. You are not waiting on a single sequential queue.

What you do while it runs

Nothing. Close the tab. The task continues in the background regardless of whether your browser is open. You get an email when it finishes with a link to download results. The Uploads & Results page also shows live progress if you stay logged in — a percentage bar plus a running count of each status.

For very large lists (250K+), we recommend kicking off the task at the end of your workday and grabbing results in the morning. Not because it takes that long, but because checking in obsessively does nothing productive.