The Horde Project was founded in 1998 by Jon Parise and Chuck Hagenbuch. IMP (Internet Mail Program), the webmail component of Horde, was one of the original applications in the Horde framework.
Horde and IMP grew as part of a groupware framework:
- 2000: Horde 2.0 released with IMP as a core application
- 2001: IMP 3.0 with improved IMAP support
- 2003: Horde 3.0 framework with modular architecture
- 2004: IMP 4.0 with Ajax support and improved UI
Horde expanded beyond webmail into a full groupware suite:
Key milestones:
- 2005: IMP 4.1 with calendar and contact integration
- 2007: Horde 3.2 with improved security
- 2010: Horde 4.0 (Kolab Edition) with modern architecture
- 2012: Horde 5.0 with improved mobile support
- 2014: IMP 6.0 with responsive design
Horde Webmail (IMP) is known for:
- Framework-based: Part of Horde groupware framework
- Modular: Integrates with calendars, contacts, tasks, notes
- Enterprise features: LDAP integration, ACL support
- GPL-2.0 license: Open source
The project continues with low development activity:
- 2016-2020: Maintenance releases, security updates
- 2021-Present: Minimal activity on GitHub
- GitHub: 25 stars, 24 forks, 3 open issues
- Status: Mature software with low development activity
IMP is part of the larger Horde suite:
- IMP: Webmail (Internet Mail Program)
- Ingogo: ActiveSync support
- Horde Core: Framework libraries
- Kolab: Integration with Kolab groupware
As of 2026:
- Status: ⚠️ Mature/Low Activity
- License: GPL-2.0
- GitHub: Low activity (25 stars, minimal open issues)
- Recommendation: Suitable for stable deployments, consider Roundcube for active development
| Version |
Year |
Key Features |
| IMP 3.0 |
2001 |
Improved IMAP support |
| IMP 4.0 |
2004 |
Ajax support, improved UI |
| IMP 4.1 |
2005 |
Calendar integration |
| IMP 6.0 |
2014 |
Responsive design |