What is OneSMTP

OneSMTP is a simple platform built to help developers, businesses and website owners quickly verify SMTP email configurations without having to write any code. Whether you're configuring a new mail server, troubleshooting delivery issues or simply testing credentials before deploying your application, OneSMTP makes the process fast and straightforward.

In addition to SMTP testing, OneSMTP also provides an API that allows applications and websites to send emails programmatically using simple HTTP requests.

Why was OneSMTP created

OneSMTP was originally developed to help uncover a common issue experienced by customers of several web hosting providers. Many hosting companies advertise free email hosting with their shared or cloud hosting plans. While webmail often works perfectly, customers frequently discover that sending emails using the SMTP credentials fails when integrating with websites, applications or third party software.

When this happens, support teams often point out that the web based email interface is working correctly and therefore consider the service functional, even though SMTP authentication or outgoing mail from external applications may not work as expected.

OneSMTP provides an independent way to verify SMTP connectivity and email delivery. This helps customers identify whether their SMTP configuration is working correctly and encourages greater transparency between hosting providers and their customers, without turning troubleshooting into a blame game.

Technology stack

OneSMTP is intentionally built using reliable, widely adopted technologies to keep the platform lightweight, fast and easy to maintain.

Bootstrap 5

PHP

PHPMailer

JavaScript

SMTP API

OneSMTP also offers a paid SMTP API for developers who want to send emails programmatically from their websites, applications or backend services without managing their own mail infrastructure.

If you're interested in integrating the API or would like to activate API access for your account, feel free to contact us.