To be honest, Zimbra and Citadel are targeting different segments of the email and collaboration market. Zimbra is focused on high-end enterprise installations while Citadel is focused on small to medium size organizations. They are also built using completely different architectures -- Zimbra is a rollup of a bunch of existing components (postfix, cyrus, mysql etc. etc. etc.) with a Java-server web front end on top, while Citadel contains lightweight C versions of every service it implements built into its own code. Finally, the two products are built using different development models: Zimbra is supported by a company that makes money by offering a free basic version and a commercial full version, while Citadel is a community project with only one GPL3-licensed edition.
Which one is better for you? The only way to be sure is to install both and try them out. |