Email Checker by lemlist Review
Introduction
Sending cold emails to invalid addresses isn’t just wasteful — it actively harms your sender reputation, inflates bounce rates, and tanks inbox placement. Yet most free email validators offer binary “valid/invalid” outputs — missing critical nuances like role-based addresses or catch-all domains.
lemlist’s Email Checker solves this with precision: a no-signup tool that returns four actionable statuses — Deliverable, Risky, Undeliverable, and Unknown — in under 3 seconds. In this hands-on review, we test its accuracy, practicality, and how it integrates into high-stakes outreach workflows.
What Is the Email Checker?
As described by lemlist, this tool “verifies email addresses by analyzing their status” using real-time SMTP checks and domain intelligence — not just syntax or DNS lookups.
Unlike basic validators, it distinguishes high-risk addresses (e.g., info@, admin@, or temporary inboxes) from truly safe ones — helping you protect deliverability before hitting send.
Key output statuses:
- ✅ Deliverable — High-confidence valid; safe to email
- ⚠️ Risky — May bounce or flag spam; avoid for cold outreach
- ❌ Undeliverable — Invalid, misspelled, or inactive
- ❓ Unknown — No response from server; retry or skip
Key Features
- ✅ 10 Free Checks/Day — No Signup Required — Just enter email → get result
- ✅ 4-Tier Validation Logic — Goes beyond “valid/invalid”
- ✅ Real-Time SMTP + Syntax + Domain Checks — Not just regex
- ✅ Mobile-Friendly & Instant — Results in <3 seconds
- ✅ Clear Action Guidance — “Avoid”, “Remove”, or “Proceed”
Note: Bulk verification requires a lemlist account (free trial available).
How to Use It (Step-by-Step)
- Visit https://www.lemlist.com/free-tools/email-checker
- Enter an email address (e.g., alex@zapier.com)
- Click “Check email address”
- Wait 1–3 seconds — status appears with explanation
- Act accordingly:
- ✅ Deliverable → add to campaign
- ⚠️ Risky → skip or warm via LinkedIn first
- ❌ Undeliverable → remove from list
💡 Pro Tip: Pair with lemlist’s Email Permutator to generate candidates, then verify — a powerful free two-step workflow.
Use Cases / Who Should Use This Tool
- 🎯 Cold emailers pre-cleaning lead lists
- 🚀 Founders validating early-customer emails
- 📩 Sales ops maintaining CRM hygiene
- 🧪 Growth hackers A/B testing outreach sequences
- 📊 Marketers protecting domain reputation
Ideal for anyone serious about email deliverability — not just open rates.
Pros and Cons
✅ Pros | ❌ Cons |
✔️ Granular status types (not just binary) | ✖️ 10 checks/day limit without account |
✔️ No false positives on common risky patterns (e.g., support@) | ✖️ No bulk CSV upload in free tier |
✔️ Transparent explanations for each status | ✖️ No API or export functionality |
✔️ Zero friction — no email, no signup | ✖️ “Unknown” results require manual follow-up |
Is It Free?
Yes — with a fair limit:
- 10 verifications/day, no account needed
- Unlimited checks with a free lemlist trial (14 days, no card)
All checks use live validation — not cached data.
Alternatives
- Hunter Verifier — 25 free/month, but only “valid”/“invalid”
- ZeroBounce Free Tier — 100 credits, then $16/mo
- MailboxValidator — free API, but rate-limited
lemlist’s tool stands out for granular risk intelligence and zero-barrier access — especially when combined with their ecosystem.
Final Verdict
⭐ 4.7 / 5 — A rare free tool that treats sender reputation as seriously as conversion. By flagging “Risky” addresses — not just broken ones — it helps prevent long-term deliverability damage that takes months to fix. For solopreneurs and lean teams, it’s the most responsible first line of defense before any outreach campaign.
Highly recommended as a standard step in lead validation workflows.
FAQ
Q1: What makes an email “Risky”?
A: Common triggers: role-based addresses (info@, hello@), catch-all domains, free providers (Gmail/Yahoo for B2B), or low-engagement histories.
Q2: Can I check Gmail or Outlook addresses?
A: Yes — but personal emails are often marked Risky for B2B cold outreach (lower reply rates, higher spam complaints).
Q3: Does it detect disposable emails (e.g., TempMail)?
A: Yes — many are flagged Undeliverable or Risky based on domain reputation.
Q4: How accurate is the “Deliverable” label?
A: >95% accurate per internal lemlist benchmarks — but no validator is 100%. Always warm new domains gradually.
Q5: Can I use it with my ESP (e.g., Mailchimp, HubSpot)?
A: Not directly — but clean your list before upload to avoid bounces and list fatigue.