Quick vs Deep Verification

Choose the right verification mode for your list. Quick mode is fast and affordable; Deep mode adds SMTP mailbox verification and extra intelligence checks for higher confidence.

At a glance

What each mode runs

Checks in both modes (1-21 + 23)

Phase 1 — Hard-fail checks (instant reject, score set to 0):

Phase 2 — Soft signals (trust score modifiers):

Deep-only checks (22, 24-25)

SMTP verification connects to the recipient's mail server and checks whether the specific mailbox exists. This catches addresses that look valid on paper but will bounce in practice.

Note: Large providers like Gmail, Yahoo, and Outlook use catch-all configurations — their servers accept all addresses at the SMTP level regardless of whether the mailbox exists. For these domains, SMTP status shows as "skipped" and the score relies on the other checks.

When to use Quick mode

• Routine list hygiene — regular re-verification of lists you have already cleaned
• Re-verification of recently verified lists — Quick mode catches newly invalid addresses without the extra cost
• Lists from your own signups — addresses collected through your own forms with double opt-in are generally reliable
• Budget-conscious verification — when you need to verify a large list and want to minimize credit usage

When to use Deep mode

• Purchased or rented lists — these often contain dead addresses, spam traps, and recycled domains. SMTP verification catches addresses that look valid but will bounce.
• Important campaigns — product launches, investor communications, or anything where a high bounce rate would be damaging
• Leads from unknown sources — contest signups, scraped data, or any list where you cannot verify the collection method
• First-time verification of old lists — if a list has never been verified or has not been checked in 6+ months, Deep mode gives you the highest confidence

Speed comparison

Deep mode is slower because it establishes SMTP connections to verify each mailbox. The job runs in the background either way — you can close the browser and come back when it is done.

How to select your mode

Open Email Verifier in the sidebar. The mode selector is at the top of Step 1 (Prepare) — you see the Quick vs Deep choice before entering any emails. Each mode card has a "See all checks" expandable link so you can review exactly what is included. You can also pass the mode parameter when using the API.