You may think I'm a glutton for punishment trying to install more software of release candidate quality, but I've been tinkering with Zimbra for some time and wanted to give this new version a whirl.
For those of you who don't know what Zimbra is, it is a mail, calendaring and groupware solution. It is one of the so called "Exchange Killers" that provides both web based and client based access to mail and calendaring. It is probably most noted for its very slick Ajaxy Web 2.0 interface. It feels like you're using a desktop application even when using Zimbra's web client.
Zimbra operates under an open source license, but only part of the product is open source. There are two primary flavors of Zimbra, the Network Edition (i.e. the commercial version) and the open source edition. The primary differences between the two are that the Network Edition (at least the Professional version) provides client synchronization for Outlook (on Windows) and iCal (on Mac OS X). Allegedly there is work underway to provide synchronization with Evolution on Linux as well. The network edition also provides the option of adding on wireless clients that can sync with the server OTA using an activesync hook (for added cost) along with backup facilities, support and clustering. A full comparison is available on the Zimbra web site. The professional version is borderline (at best) for the "cheap" category that is one of my criteria at $35 per seat with a minimum of 25 seats. So I went ahead and installed the open source version (as a side note, we're also exploring using this in my workgroup, for which Zimbra offered a substantial academic discount).
I've been intrigued by Zimbra for quite some time, in that it offers a great interface for users and claims to have much simpler administration than Exchange. I like the potential for Outlook and ICal clients, even if that is only in the professional version. While there are a number of open source groupware solutions out there, the most directly comparable is likely Scalix. I have also evaluated Scalix, with its primary advantage being full blown client access from Outlook for up to 25 users in their "Community" edition. Scalix also does a slightly better version of playing nicely with existing resources on your server, but still takes over many services and ports. Zimbra is a one stop solution, which means it takes over your web server, MTA, databases, tomcat, etc. That means it is easy to install, but requires its own server (or virtual servers, as I use VMWare's free VMWare server for testing). However, it offers no iCal/iSync pathway.
The other issue for both Zimbra and Scalix is that while their web clients are rather slick, they are bandwidth intensive. This makes it impractical when traveling and using slower connections. Some people have installed Squirrelmail or Roundcube as backup webmail systems, but that seems suboptimal. So I was intrigued when I heard the latest release candidate of Zimbra included an html only web client as a component. I just had to try it out.
Installing Zimbra isn't hard if you have one of the requisite systems for which binaries already exist. Binaries are available for Fedora Core 4 and 5, Redhat Enterprise Linux 4, and several other platforms (including Ubuntu and Mac OS X). I used the Redhat version, on VMWare server running RHEL 4. I see no reason why it should be any different if you were using Cent OS, or probably even Fedora.
Installation is a matter of ungzip/untar the binary and run the install script. You are prompted with some confirmations and ultimately one configuration step (changing the admin password). If all goes well, there is little interaction. It is important for Zimbra (the same goes for Scalix) to have a FQDN that resolves correctly. Since I was running on a virtual server behind a router, I needed to configure the etc/hosts file to pull that off. It is important to follow the instructions on this configuration to the letter. I spent the better part of the evening struggling with some unhelpful messages about the database being unable to connect. But making sure my hosts file looked exactly like the one in the docs, made it work just fine in the end. I also needed to make sure I manually turned off Sendmail as it also says in the documentation.
I did notice that the install script really takes care of everything - certificates, spam settings, everything. That was a bit nicer than my Scalix experience in which you need to do a bit of hacking to get SSL working. It also configures SMTP authentication.
I then tried to connect to the Zimbra administration console. It failed. I realized that I hadn't punched the holes in the firewall for all of the necessary ports. This should be a more explicit part of the installation process, rather than just telling you to turn off the firewall completely.
After that I was into the Administration console. The admin console itself is a quite user friendly Ajax application itself.
It was very easy to create a new user, and configure simple settings on the server. It hiccuped when I tried to configure the Documents portion, with a generic error, but otherwise worked flawlessly.
A quick tour of Zimbra itself, shows some of the great features of the application.
The webmail interface is fast and easy to use. With large volumes of email, I find interfaces where you have to jump in and out of directories and click on check boxes to be quite cumbersome. Zimbra excels in this area.
It even has some useful context sensitive menus that pop up around relevant text in your emails. Such as when someone sends a message concerning a date, you can mouse over it for your schedule or right-click (in the browser) to add an appointment.
This is further enhanced by keyboard shortcuts that help you quickly navigate within and between sections. I'm a UI-clicker myself, but the shortcuts can speed up work flow.
There are also address book,
calendar, and 
documents sections.
Getting back to the reason why I tried this update of Zimbra in the first place, there is also easy access to a "basic" (HTML Only) version of the UI. Upon login you can click on the basic html link and you are taken to a nearly identical login box. Once inside the interface indeed looks like an HTML version of Zimbra.
The webmail and address book sections behaved well. Unfortunately the calendar section is absent. This was disappointing, though it is possible it will appear in future versions.
Of course the open source edition is missing the iSync and Outlook sync components. This makes this edition of Zimbra problematic for road warriors who may be needing access to their calendar offline (email can be synced up through any imap or pop client). Allegedly Zimbra is working on offline sync through the standard web interface in the near future. That could take this version over the top, and make it a complete package without the need for Outlook.
Update (21 Dec): I realized that I hadn't actually tried to get email in to my Zimbra server, assuming this wouldn't be hard. That wasn't true. I had a lot of trouble with mail being rejected or something Zimbra calls "deferred" (which means it is stored in a queue but not sent to mailboxes). I tried reconfiguring my hosts file, but that didn't help. It turned out that the problem had to do with Zimbra running inside my router with an internal IP address that was mapped to an external one. There were good instructions for setting up BIND to handle this situation on the Zimbra wiki.
For those of you who don't know what Zimbra is, it is a mail, calendaring and groupware solution. It is one of the so called "Exchange Killers" that provides both web based and client based access to mail and calendaring. It is probably most noted for its very slick Ajaxy Web 2.0 interface. It feels like you're using a desktop application even when using Zimbra's web client.
Zimbra operates under an open source license, but only part of the product is open source. There are two primary flavors of Zimbra, the Network Edition (i.e. the commercial version) and the open source edition. The primary differences between the two are that the Network Edition (at least the Professional version) provides client synchronization for Outlook (on Windows) and iCal (on Mac OS X). Allegedly there is work underway to provide synchronization with Evolution on Linux as well. The network edition also provides the option of adding on wireless clients that can sync with the server OTA using an activesync hook (for added cost) along with backup facilities, support and clustering. A full comparison is available on the Zimbra web site. The professional version is borderline (at best) for the "cheap" category that is one of my criteria at $35 per seat with a minimum of 25 seats. So I went ahead and installed the open source version (as a side note, we're also exploring using this in my workgroup, for which Zimbra offered a substantial academic discount).
I've been intrigued by Zimbra for quite some time, in that it offers a great interface for users and claims to have much simpler administration than Exchange. I like the potential for Outlook and ICal clients, even if that is only in the professional version. While there are a number of open source groupware solutions out there, the most directly comparable is likely Scalix. I have also evaluated Scalix, with its primary advantage being full blown client access from Outlook for up to 25 users in their "Community" edition. Scalix also does a slightly better version of playing nicely with existing resources on your server, but still takes over many services and ports. Zimbra is a one stop solution, which means it takes over your web server, MTA, databases, tomcat, etc. That means it is easy to install, but requires its own server (or virtual servers, as I use VMWare's free VMWare server for testing). However, it offers no iCal/iSync pathway.
The other issue for both Zimbra and Scalix is that while their web clients are rather slick, they are bandwidth intensive. This makes it impractical when traveling and using slower connections. Some people have installed Squirrelmail or Roundcube as backup webmail systems, but that seems suboptimal. So I was intrigued when I heard the latest release candidate of Zimbra included an html only web client as a component. I just had to try it out.
Installing Zimbra isn't hard if you have one of the requisite systems for which binaries already exist. Binaries are available for Fedora Core 4 and 5, Redhat Enterprise Linux 4, and several other platforms (including Ubuntu and Mac OS X). I used the Redhat version, on VMWare server running RHEL 4. I see no reason why it should be any different if you were using Cent OS, or probably even Fedora.
Installation is a matter of ungzip/untar the binary and run the install script. You are prompted with some confirmations and ultimately one configuration step (changing the admin password). If all goes well, there is little interaction. It is important for Zimbra (the same goes for Scalix) to have a FQDN that resolves correctly. Since I was running on a virtual server behind a router, I needed to configure the etc/hosts file to pull that off. It is important to follow the instructions on this configuration to the letter. I spent the better part of the evening struggling with some unhelpful messages about the database being unable to connect. But making sure my hosts file looked exactly like the one in the docs, made it work just fine in the end. I also needed to make sure I manually turned off Sendmail as it also says in the documentation.
I did notice that the install script really takes care of everything - certificates, spam settings, everything. That was a bit nicer than my Scalix experience in which you need to do a bit of hacking to get SSL working. It also configures SMTP authentication.
I then tried to connect to the Zimbra administration console. It failed. I realized that I hadn't punched the holes in the firewall for all of the necessary ports. This should be a more explicit part of the installation process, rather than just telling you to turn off the firewall completely.
After that I was into the Administration console. The admin console itself is a quite user friendly Ajax application itself.
It was very easy to create a new user, and configure simple settings on the server. It hiccuped when I tried to configure the Documents portion, with a generic error, but otherwise worked flawlessly.
A quick tour of Zimbra itself, shows some of the great features of the application.
The webmail interface is fast and easy to use. With large volumes of email, I find interfaces where you have to jump in and out of directories and click on check boxes to be quite cumbersome. Zimbra excels in this area.
It even has some useful context sensitive menus that pop up around relevant text in your emails. Such as when someone sends a message concerning a date, you can mouse over it for your schedule or right-click (in the browser) to add an appointment.
This is further enhanced by keyboard shortcuts that help you quickly navigate within and between sections. I'm a UI-clicker myself, but the shortcuts can speed up work flow.
There are also address book,
calendar, and 
documents sections.
Getting back to the reason why I tried this update of Zimbra in the first place, there is also easy access to a "basic" (HTML Only) version of the UI. Upon login you can click on the basic html link and you are taken to a nearly identical login box. Once inside the interface indeed looks like an HTML version of Zimbra.
The webmail and address book sections behaved well. Unfortunately the calendar section is absent. This was disappointing, though it is possible it will appear in future versions.
Of course the open source edition is missing the iSync and Outlook sync components. This makes this edition of Zimbra problematic for road warriors who may be needing access to their calendar offline (email can be synced up through any imap or pop client). Allegedly Zimbra is working on offline sync through the standard web interface in the near future. That could take this version over the top, and make it a complete package without the need for Outlook.
Update (21 Dec): I realized that I hadn't actually tried to get email in to my Zimbra server, assuming this wouldn't be hard. That wasn't true. I had a lot of trouble with mail being rejected or something Zimbra calls "deferred" (which means it is stored in a queue but not sent to mailboxes). I tried reconfiguring my hosts file, but that didn't help. It turned out that the problem had to do with Zimbra running inside my router with an internal IP address that was mapped to an external one. There were good instructions for setting up BIND to handle this situation on the Zimbra wiki.
>Unfortunately the calendar section is absent.
Did you check Calendar-feature is turned ON?
Here is how to check:
Login to Admin Console
Click on Class Of Service
Edit- 'default' cos
Click on Features-tab
Thanks for the tip. Everything is checked in that tab. The calendar appears normally in the "advanced" client, just not in the "basic" client.