In most cases the mailboxlayer API's SMTP check is entirely accurate when it comes to detecting whether or not an email address actually exists. We are saying "most" cases because certain mail servers tend to suddenly behave in unexpected ways and cause trouble out of nowhere, which may decrease the effectiveness of "pinging" a mail server via SMTP at times.

Combined with all other mailboxlayer validation tools, however, there is no better way to separate low-quality addresses from high-value email contacts and to successfully keep fraudulent users out of your system.

Generally, sending email to free email addresses like "Gmail" or "Yahoo!" is perfectly okay. For certain types of email campaigns, however, it might make sense to sort out users utilizing free email providers in order to reduce bounce rates.

See the API's Documentation for details.

Email addresses like "mailinator.com" or "trashmail.com" are using disposable email provdiders, which offer an anonymous way to create a one-time email address. These inboxes are often publicly visible and associated with fraudulent behaviour. We highly advise against approving these types of email addresses in your system or list of recipients.

See the API's Documentation for details.

Yes. Since we understand that your API requests contain may sensitive data, we offer paid customers the possibility to access the API and all data provided by and processed through it via industry-standard 256-bit HTTPS encryption.

See the API's Documentation for details.

Pricing is based on the number of monthly API Requests offered for each individual Subscription Plan. Accessing any type of mailboxlayer API data using a valid API Access Key counts as one "API Request".

Users will be automatically notified via e-mail and on their Account Dashboard once at least 75%, 90%, and 100% of their monthly API Request allowance has been reached.

Since our team is aware that requirements may be very variable, a Subscription Plan's Request volume may be exceeded by a maximum of 20%, which means that the actual hard-limit of - e.g. - the Professional Plan is 120,000, instead of 100,000.

Please rest assured that exceeding the monthly API Request allowance will not cause any additional charges.

The mailboxlayer API's system status is being closely monitored around the clock. Since every effort is made to ensure the highest possible level of consistency, we are happy to announce that our API's uptime is at around 99.9%. At the current stage we are not offering any public statistics, but we will be happy to provide you with recent uptime reports - ask us »

The Free Plan is set out to be a "trial version" without a time limit, offering a volume of 250 monthly API requests.

Paid Subscription Plans feature significantly higher API Request volumes, ensure secure datastreams via 256-bit HTTPS Encryption, include unlimited and prioritised technical support, and offer a variety of must-have API functionalities.

In order to test the API and to get an idea of the product, you can simply sign up for the Free Plan.

As soon as you or your application requires more than 250 API requests per month and more professional API functionality, you would be well-advised to sign up for one of the paid Subscription Plans, starting at only USD 9.99 per month, or at a 20% discount - if you decide to pay anually.

Payments can be made via Credit Card (Visa, MasterCard, Discover, Diner's Club). You can change your payment method at any given time in the Payment section of your Account Dashboard.

Yes. If you choose annual billing, the total price of your Subscription Plan will be 20% lower than the total amount you would pay with a monthly payment frequency.