Been running Zimbra Open Source edition for just about 205 days now (checked our uptime ) and it has been a good solution so far.
However, one thing that has been an issue is the speed.
We are running a Quad Xeon 3GHz server with 2 gigabytes of memory running Ubuntu 6.10.
We probably have around 40 odd user accounts, 100 or so aliases and perhaps 2 dozen distribution lists, hosting more than 10+ domains.
And so the issue with speed comes down to that many of our users are complaining that they get network errors while using the Zimbra Web/Ajax interface. It has gotten progressively worse over time, in particular, since I last added a new domain to Zimbra and created 8 users for that domain about a week ago.
I do realize a couple of issues which may be related. For example, 2 gigabytes of memory for Zimbra is realistically too little. Memory gets quickly maxed out after starting Zimbra services and hovers around 1500MB out of the 2027MB, while swap space is around 1430MB out of 2863MB (in an ideal world, swap space should be next to none, right?). In addition, the typical load average of the server is around 4.00 - 5.00, although this can easily go up to 9.0 (have never seen figures that high on our other servers). So, one of the things I will be doing is upgrading memory.
However, I also believe its also to do with the Ajax interface being less than responsive on some machines, in particular the less powerful client desktop, and so we are considering our options and whether upgrading to the Zimbra Network Edition. Does ZNE have any inherent speed improvements over the Open Source Edition (ie, in the software package itself or in the web interface?)?