| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | Yes | — |
| Open source | — | — |
| Web | Yes | Yes |
| Windows | Yes | — |
| macOS | Yes | Yes |
| Linux | Yes | Yes |
| iOS | Yes | — |
| Android | Yes | — |
| API | Yes | Yes |
| Self-hosted | Yes | Yes |
| Plans published | 4 | 1 |
| Spec score · Mail Server Software | 8.4 (#2) | 8.3 (#4) |
| Deployment | The product is downloadable for Linux and Windows and offers Docker images and Kubernetes deployment with AxiHelm. | Citadel can run in Docker, through a Linux build script, from source, or via a hosting provider. |
| Support | The support page says business and channel support engineers are available around the clock, with an average response time under two hours for all issue types. | Support is provided through an active user and developer community, an online knowledge base, a support forum, and a mailing list. |
