SMTPing Review: Email Validation Tool vs ClearOut Compared

What Is Email Validation and Why Does It Matter?

Every time someone signs up for your email list, there's a chance the address they gave you is either mistyped or completely fake. That might not sound like a big deal, but it directly impacts your email sender reputation. When you consistently send to invalid addresses, email service providers take notice — and the consequences range from landing in the spam folder to having your emails blocked entirely.

Email validation tools solve this problem by checking whether an address is real and deliverable before you ever hit send. They simulate the connection process without actually sending an email, giving you a verdict on each address in your list. It's a straightforward concept, but choosing the right tool matters — especially when accuracy and pricing vary so widely across the market.

SMTPing Pricing: Monthly Credits for a One-Time Price

What makes SMTPing stand out from virtually every other email validation tool is its pricing model. Available as a lifetime deal on AppSumo, it offers monthly recurring credits for a single upfront payment — something almost unheard of in this space.

Tier 1 starts at $39 and gives you 30,000 email validations per month, every month, forever. For context, ClearOut charges $174 for a one-time batch of 30,000 credits, with no renewal. If you need more volume, SMTPing scales up to Tier 4 at $349, which includes 1,000,000 monthly validations plus 250,000 bonus one-time credits. Starting at Tier 2, you also get extra one-time credits on top of the recurring allotment.

The pricing makes this particularly interesting for agencies. If you're already cleaning email lists for clients, you could easily charge market rates for validation services while your actual cost is a one-time investment. At ClearOut's pricing of $1,100 for 1,000,000 credits, the math on ROI gets very attractive very quickly.

SMTPing Interface and Features

The SMTPing interface is clean and minimal — perhaps a little too minimal. The dashboard shows basic verification analytics, a credit usage meter, and a daily validation graph for the current month. There's no option to view historical data beyond the current month, and if you're validating for multiple businesses, everything gets lumped together in one view.

The core functionality breaks down into two main tools. Single email validation lets you check individual addresses in real time, which is useful for in-person signups or quick spot checks. You type in an address, hit check, and the tool runs through its verification process, even showing a command-line style readout of the connection attempt. Results come back as valid, invalid, unknown, or catch-all.

Bulk email validation is where most users will spend their time. You upload a CSV export from whatever email platform you use — Mailchimp, ActiveCampaign, ConvertKit, you name it — select the email column, and let it rip. There's also a separate CSV validator tool that checks your file for formatting errors before you even run the validation, which is a surprisingly handy utility when dealing with messy exports.

Head-to-Head: Testing 1,600 Emails on Both Platforms

To get a real sense of accuracy, we ran the same list of 1,591 email addresses through both SMTPing and ClearOut. Starting with single email validation, there was an immediate difference in clarity. Testing a made-up address (eddie@pearljam.com), ClearOut returned a definitive "invalid" result. SMTPing flagged it as failing due to graylisting — accurate, but less clear for someone who just wants a yes-or-no answer.

The bulk results told a more nuanced story. SMTPing identified 1,331 valid addresses, 158 invalid, 56 catch-all, and 41 unknown, with 5 duplicates. ClearOut found a higher number of technically valid addresses but then applied additional filters — removing disposable accounts, role-based addresses (like support@ or billing@), and other risky categories — to arrive at 1,307 "guaranteed deliverables."

ClearOut's extra categorization is genuinely useful. It breaks results into disposable accounts, free email providers (Gmail, Yahoo, AOL), role accounts, and syntax errors. This granularity helps you make better decisions about which addresses to keep. SMTPing gives you the basics — valid, invalid, unknown, catch-all — and leaves the rest to you.

Results Comparison: Where the Two Tools Disagree

The overall numbers between the two tools were close, but the devil is in the details. Out of SMTPing's 1,331 valid addresses, 67 were flagged as non-deliverable by ClearOut. Going the other direction, ClearOut marked 37 addresses as good that SMTPing rejected. That's roughly 100 email addresses where the two tools fundamentally disagree.

On a list of 1,600, having 100 addresses in dispute might not sound catastrophic, but it matters more than you'd think. If even half of those disputed addresses are truly invalid and you send to them, that's enough to ding your sender reputation. The safest approach would be to cross-reference disputed addresses on a third tool or segment them into a separate test send.

It's worth noting that neither tool is definitively "right" in these disagreements. ClearOut has years of data and refinement behind it, which naturally builds confidence. But SMTPing could be catching things ClearOut misses on some of those 37 addresses. Without sending actual test emails to every disputed address, there's no way to know for certain.

Integrations and Export Options: ClearOut's Big Advantage

This is where ClearOut pulls decisively ahead. ClearOut offers native integrations with WordPress, Lemlist, Mailchimp, Moosend, ActiveCampaign, MailerLite, Zapier, Make, and more. The WordPress integration is particularly valuable — it validates email addresses at the point of signup, before they ever touch your email list. That kind of real-time validation at the form level is a game-changer for list hygiene.

SMTPing currently has zero integrations. Everything runs through their web interface, meaning you're limited to uploading CSV files and downloading results. For agencies or anyone managing multiple client lists, this adds friction to every single validation job.

The export options tell a similar story. ClearOut lets you download guaranteed deliverables, deliverables with risk, non-deliverables, full results with detailed columns, or a custom combination of categories. SMTPing gives you three options: all results, clean results, or a PDF report. If you want valid plus catch-all addresses but not unknown ones, you'll need to download everything and filter manually in a spreadsheet. It's not a dealbreaker, but it's the kind of quality-of-life gap that adds up over time.

Final Verdict: A 6.9 With Serious Upside Potential

SMTPing earns a 6.9 out of 10 — a score that reflects a tool with solid fundamentals and a killer price point, held back by a lack of polish and missing features. The validation results are in the same ballpark as ClearOut, which is encouraging for a newer tool. But the absence of integrations, limited export options, and bare-bones interface mean it can't compete feature-for-feature with established players.

Here's the thing though: the pricing model makes it almost impossible to lose money on this deal. Even at its limitations, if you validate email lists a few times a year, the Tier 1 plan pays for itself after a single use compared to what you'd spend on ClearOut or similar services. For agencies, Tier 2 through Tier 4 could genuinely turn into a profit center — buy once, validate monthly, charge clients market rates.

The recommendation is to buy at whatever tier matches your volume, accept that you'll be doing some manual work around exports and integrations for now, and bet on the tool improving over time. If those integrations and export refinements show up in future updates, this could easily become one of the better value LTDs in the email space.

Watch the Full Video

Prefer watching to reading? Check out the full video on YouTube for a complete walkthrough with live demos and commentary.