Mailboxlayer Alternatives: When an API Quota Is the Wrong Shape for Your Lists

Mailboxlayer is built for developers checking addresses one request at a time, and it is cheaper than a flat plan for small API volume. Its Basic plan is $14.99 a month for 5,000 requests on the pricing page we read today. If your real work is verifying CSV lists, or you outgrow request quotas, SimpleVerifier Pro is $39 a month, with the first 100,000 checks a month at full speed, then slower, never cut off. Its API is part of the same plan, with 10,000 calls a month included.

Compare your monthly cost →

What Mailboxlayer charges

From the Mailboxlayer product page, read on 9 November 2026:

Plan	Monthly	Yearly	Requests a month	Overage per extra call
Free	$0	$0	100	None listed
Basic	$14.99	$161.99 (10% off)	5,000	about $0.012
Professional Plus	$74.99	$787.99 (12.5% off)	50,000	about $0.006
Enterprise Plus	$249.99	$2,549.99 (15% off)	250,000	about $0.004
Custom	Contact sales	Contact sales	Unlimited, per the page	Not listed

What each plan includes, per the page:

• Free: syntax and typo check, free and disposable provider detection, quality score, real-time SMTP, MX record check. Not for commercial use.
• Basic: everything in Free, plus catch-all detection and commercial use.
• Professional Plus: adds a bulk endpoint of 25 emails per request.
• Enterprise Plus: a bulk endpoint of 100 emails per request.

On overage, the page says fees apply after you reach 100% of the allowance, and gives an example of 10,000 overage calls: $119.92 on Basic, $59.99 on Professional Plus and $40.00 on Enterprise Plus. It notifies you at 75%, 90% and 100%.

When a request quota is the right shape

A quota fits when each address arrives one at a time:

• A signup or checkout form that checks the address as people type it.
• A small app with a steady, predictable number of new users.
• A product where you want to pay a small fee and nothing more.

If you check a few thousand addresses a month this way, $14.99 is a lower bill than any flat plan, ours included.

When it stops fitting

• CSV lists. A list of 80,000 is 80,000 requests. On Professional Plus ($74.99, 50,000 requests) the overage on the extra 30,000 calls at the page's per-call rate is about $180, which makes the month about $255. That figure is our arithmetic from the page's rate, so check it against your own bill.
• Bulk endpoint only on higher plans. 25 emails per request starts at Professional Plus.
• Re-checks. Each pass spends the same quota again.

The email list decay calculator estimates how much of your list needs a re-check.

What a flat plan including the API looks like

SimpleVerifier Pro is $39 a month (or $390 a year). Email verification is the first 100,000 checks a month at full speed, then slower, never cut off.

Per the pricing page, Pro also includes:

• CSV upload, up to 100,000 rows per file
• Real SMTP mailbox checks, not just syntax
• Catch-all, disposable and role-address detection
• Export valid, risky or invalid separately
• An email finder (name and company to a verified address) and website enrichment
• API: 10,000 calls a month included, then $1.50 per 1,000

Only email verification has the 100,000 full-speed fair-use line. The finder and API are not unlimited.

For signup forms, our API quickstart and rate limits guide cover the call format. If your volume is files, the API or CSV upload guide helps you choose.

How to split the work

Job	Better fit
Check one address at signup	A request-based API, either one
Clean a purchased or exported list	A CSV upload
Check a CRM before a campaign	A CSV upload, then import
Check a form plus lists	One plan that covers both

What about catch-all domains?

A catch-all domain accepts every address at the SMTP step, so a standard check can't confirm a single mailbox there. That is true for every verifier. Treat catch-all rows as their own group: send to them slower and watch the bounce rate. Our guide to what to do with catch-all emails covers the options, and you can test a domain with the catch-all checker.

How to compare results fairly

1. Pull 300 to 500 random rows with the email list sampler.
2. Verify them in Mailboxlayer and in SimpleVerifier on the same day.
3. Line up the results with compare email lists.
4. Look at the disagreements, especially valid in one and risky in the other.

We don't publish accuracy figures for other tools, and we don't publish one for ours. The sample test on your own data is the number that matters.

Questions to ask before you switch

• How many requests do I use a month? Add signups and list checks.
• Do I have overage? The per-call fee can double a bill.
• Do I need catch-all detection? It is not on Mailboxlayer's Free plan.
• Do I call it from code, or upload files? Choose the tool for your main job.

Quick answers

• Is Mailboxlayer good for lists? Not as its main use. The page describes a request API and bulk endpoints from Professional Plus.
• Can I keep Mailboxlayer for signups and use SimpleVerifier for lists? Yes, if signups are small. Two vendors is one more bill, though.
• Does Free work commercially? The page lists commercial use as No on Free.

Try it on your own list

Upload a sample at /verify. The first 100 checks are free with a Google sign-in, no card.

Pro, $39 a month: Unlimited email verification.* Never metered, never cut off. See pricing.

*Fair use: the first 100,000 checks a month at full speed, then slower, never cut off.

More: email verification API comparison, email verification API cost per month, bulk verify a CSV with the API.