Get off Zimbra now!
Although the look and feel may be pretty slick and give you lots of flexibility in creating widget and manipulating the inside pages, this platform offers a little or almost not existent support in all that is community management related. First of all, it doesn't send automatic email digests (unless you fight for them); second, it doesn't allow to see list of members and to measure engagement in a personalized manner; third, there is no customer support and their internal links keep changing so you have no access to documents that explain the features; forth, it doesn't work on mobile. We used it for over two years and they did not provided any product enhancements. We are now finally transitioning to Higherlogic.