mailboxlayer
Validate email addresses and check mailbox existence via API.
Read docs Updated 2026-06-17
What is mailboxlayer?
mailboxlayer is an HTTPS API that validates email addresses and checks mailbox existence using API key authentication.
It supports applications that need to verify email data quality during user signups or list management.
What you can build with mailboxlayer
Real-time signup validation
Block fake or undeliverable email addresses at user registration time to reduce spam accounts and improve list quality.
Bulk email list cleaning
Process existing marketing lists to remove invalid mailboxes before campaigns, lowering bounce rates and protecting sender reputation.
Lead form verification
Validate contact emails collected from landing pages or sales forms to ensure sales teams only receive working addresses.
Get started with mailboxlayer
- 1Sign up at mailboxlayer.com and obtain your free API key
- 2Read the documentation to locate the validation endpoint
- 3Append your target email and access_key to the HTTPS request URL
- 4Send a GET request and inspect the JSON response fields
- 5Handle the 'mx_found' and 'smtp_check' results in your code
mailboxlayer: pros & cons
Pros
- +Confirms active mailboxes via SMTP checks
- +Simple API key authentication over HTTPS
- +Fast response times suitable for real-time use
- +Clear JSON responses with detailed flags
Cons
- –Free tier limited to 250 requests per month
- –Cannot detect all catch-all or disposable domains
- –Requires internet access and external dependency
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Frequently asked questions
An HTTPS API that validates email addresses and reports whether they correspond to active mailboxes.
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