What webmail does Bluehost use?
Bluehost webmail is Horde webmail. Horde webmail is webmail for the Horde application stack, which runs web applications like RoundCube and SquirrelMail. At this time there are no plans to offer an alternative webmail product.
The webmail product is not open source. However, the web server and database software that powers webmail are both open-source projects.
If you require webmail software that is installed on your own hosting account, please contact our sales team to discuss this option.