IceWarp is a mail server with a collaboration suite attached: webmail, calendars, contacts, team chat, video conferences and online document editing, all from one Czech vendor. It is aimed at companies that want an alternative to Microsoft 365 but with the option of keeping everything on their own hardware.
IceWarp is shareware — you can try it, and a licence from the vendor is needed for continued use. The current version is 14.3.0.12 (September 2026).
IceWarp at a glance
| Latest version | 14.3.0.12, released 15 September 2026 |
|---|---|
| Licence | Shareware (conditionally free) |
| Editions | Core, Essential and Business; cloud-hosted or self-hosted |
| Server systems | Windows Server 2016 or newer; Rocky Linux 8 and 9, AlmaLinux 9, RHEL 9 |
| Database | MariaDB 10.5+ or MySQL 8.0+ for production; SQLite only for limited use |
| Deployment | Installers for Windows and Linux, plus VMware, Hyper-V and Docker images |
What it includes
- Mail server with anti-virus and anti-spam built in.
- Webmail plus desktop clients, with PGP support, and Outlook synchronisation.
- TeamChat — group channels with files, mentions and pinned messages — and one-to-one chat.
- Video conferences for large audiences, with recording, and webinar mode in the top edition.
- Documents: collaborative editing of Word, Excel and PowerPoint files.
- Files — cloud storage with synchronisation.
- Calendars, tasks, notes and contacts, with a booking feature in the top edition.
- Exchange ActiveSync for phones, and modern sign-in through Microsoft, Google or Apple accounts.
- Migration tools from Exchange and Kerio.
Planning a self-hosted installation
The vendor publishes concrete numbers for a thousand users, which are useful even at smaller scale:
- Application server: 4 cores, 16 GB RAM, 200 GB disk — and that is only for the system, configuration and logs.
- Mail storage: at least 2 GB per user, on top of the above.
- Database server: 2 cores, 8 GB RAM, 50 GB disk.
- Full-text search adds another 4 cores, 8 GB RAM and roughly a fifth of the indexed data volume.
Updates restart the service. The vendor estimates up to fifteen minutes of downtime when moving between minor versions, so plan the window.
Download and install
- Click the Download button at the top of this page and unpack the archive.
- Install on a supported system — Windows Server 2016 or newer, or an enterprise Linux release. Administrator or root rights are required.
- Set up MariaDB or MySQL first. SQLite works only for limited scenarios, not for a production server.
- Configure DNS: MX, SPF, DKIM, DMARC and reverse DNS. Without them mail will not be delivered reliably, no matter how good the server is.
- Install a TLS certificate before opening the server to the internet.
Where it fits, and where it does not
Good fit: a company of dozens to thousands of users that wants mail, chat, video and documents from one vendor, with the choice of self-hosting for data-residency reasons.
Poor fit: a small office that needs only mail — hMailServer on Windows or Mail-in-a-Box on Linux are free and do that job. Also a poor fit for anyone without a sysadmin: this is a platform, not an application.
IceWarp vs. alternatives
| Tool | How it compares |
|---|---|
| hMailServer | Free and open source, Windows, mail only — no webmail, chat or documents |
| Mail-in-a-Box | Free, Linux, includes webmail and calendars; takes over the whole machine and is not configurable |
| Microsoft Exchange | The corporate standard; licensed per user and tied to the Microsoft ecosystem |
| Zimbra, Zextras | Comparable collaboration suites, with an open-source lineage |
FAQ
Is IceWarp free?
It is shareware — free to try, with a licence from the vendor for continued use.
Can I run it on my own server?
Yes. Self-hosted deployment is supported on Windows Server and enterprise Linux, including virtual appliance and container images.
Does it replace Microsoft 365?
It covers the same ground — mail, calendars, chat, video and document editing. Whether it replaces Microsoft 365 for you depends on how deeply your work is tied to Microsoft’s own applications.
What database does it need?
MariaDB 10.5 or newer, or MySQL 8.0 or newer, for production use.
How much storage per user?
The vendor’s guidance is at least 2 GB per user for mail, on top of the server’s own requirements.
Is there a free mail server instead?
Yes — hMailServer for Windows and Mail-in-a-Box for Linux, both free and both covered on this site.
