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VMware Zimbra vs. Microsoft Exchange – Follow-up


I am truly excited by the response to my Zimba vs. Exchange post from a couple weeks back. I would like to thank my readers and especially those who commented for their valued feedback. The response thus far shows that there is definite interest in alternatives to Exchange for e-mail and collaboration needs at various industries and organization types.

I believe is important to be open to competing viewpoints as well, and it is this type of interaction that causes software organizations to sit up and take notice at what they are doing right or wrong and how they can improve to expand their offerings to a wider audience and to improve the customer experience.

That said, I would like to point you to a post here & here co-written by two obvious proponents of Exchange, by the names of Michel de Rooij and Dave Stork. They put forth a rebuttal that can serve as a response (albeit somewhat flawed) to my arguments in favor of Zimbra. The comments on my post, as well as those on their sites, should be reviewed as well, as they provide constructive feedback on the validity of our arguments on both sides of the fence.

I welcome this sort of feedback and look forward to continuing the conversation throughout the Zimbra product life-cycle as well as similar or competing offerings from VMware, Microsoft and their partners.

The fact that I got a response of this magnitude not only shows that there is significant interest in Zimbra, but also that Exchange proponents feel a need to defend their territory proves that Zimbra is on their radar. I think this bodes well for competition in a Microsoft-dominated world! “No publicity is bad publicity”, so they say…

Thanks for reading!

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Basic Zimbra Cloud



I was having some issues around my Zimbra implementation just before lunch and I got to thinking… why not do a Zimbra post. Most of my peers in the virtualization and cloud industry at this point either are using Exchange by choice (or by force) or are just starting to investigate the use of Zimbra, since the VMware acquisition. I would like to talk a little bit about how I use Zimbra to help out those looking at deploying it.


My relationship with Zimbra is unique in that my previous company actually started using it officially before they started using VMware. We started at version 4.5 or 5, and the current Zimbra release is 7.1. As part of the role-out at my previous employer, I set-up a Zimbra OSS installation in my home lab environment, and eventually started using it for my custom domain e-mail services. Those that know me know I come from a Red Hat Linux background, having deployed about 100 RHEL servers in my earlier sys admin days. From that, I learned the Red Hat way of setting up LDAP, IMAP, SMTP (Postfix), CLAMAV, SPAMASSASSIN, etc. that make up a fully featured Internet mail server. Although not fully compatible with Exchange, this set-up can provide a flexible e-mail solution for companies on a budget. Coincidentally, these services also form the basis for an installation of Zimbra Collaboration Suite, with the welcome addition of MAPI compliant functionality that adds calendaring and free/busy data which are at the heart of Exchange. This makes Zimbra a drop-in replacement for Exchange, and competition is good!


I won’t discuss the architecture at my former employer, but I will discuss the architecture in my small installation. I think it’s a rather interesting blend of public and private components that show a simple use of hybrid cloud that others can extrapolate and build upon.

  • My Zimbra server consists of a single RHEL 5 (x64) VM. This machine has 2 vCPUs and 4GB RAM. As Zimbra is heavily reliant on Java, and Java likes lots of memory and no swapping, I reluctantly set a reservation of 4GB on the VM and the performance is more than adequate for my environment. I have been running Zimbra v6.0.x OSS for the past 2 years, and upgraded to 7.1 a couple weeks ago.
  • In addition to the Zimbra server, I have an external mail gateway in Chicago which is provisioned as a VM in the Rackspace Cloud. This server not only relays mail to and from the Zimbra server, but it also performs DNS resolution duties among other things. I have established a VPN between this server and my home lab network in order to get around any firewall restrictions, but also to ensure secure relay of the mail. This VM also has a backup VPN route to my home lab in the US.
  • For redundancy, I also have another Rackspace Cloud VM provisioned in their Dallas DC. This is essentially an exact duplicate of the Chicago VM, also serving DNS and SMTP duties. This VM has a VPN established between itself and my home lab in the US, Japan and also to the other Rackspace Cloud VM. It’s really nice to have this server in a separate physical location, despite it being a VM. The only thing I have to worry about it this configuration is the inter VM (i.e. VPN) traffic, which fortunately amounts to less than $1/mo.
  • In order to relay mail to and from the Zimbra server in a load-balanced fashion, I created 2 DNS MX records with the same priority. This allows incoming mail to arrive at either SMTP server and provides resiliency if one server crashes. I also created 2 DNS A records for the SMTP servers that points to each VM separately, this way when Zimbra has a mail to send it goes to each SMTP server in turn, and will retry if one of the SMTP hosts is crashed or otherwise inaccessible.
  • In order to provide mobile access, I enabled both secure IMAP and secure SMTP on the Zimbra server and then NAT these to the internal hosts behind my firewall. Believe me, it’s nice that I have a static IP for this purpose. Because my ISP allows SMTP and IMAP without issue, I connect directly over SSL from my mobile phone to the Zimbra server and have fully-featured mail access.


Diagrammatically, the setup looks something like this:






















As you can see, this is a very basic setup but is interesting in that it is a blend of public and private cloud components. One nice thing about this is that if my Zimbra server goes offline or even my entire home Internet connection, the mail will continue to queue at the SMTP servers in Rackspace’s Cloud. Once my site comes back online, the queued mail will start relaying again. All in all this makes a nice basic cloud that you can use as a lab to test out and try various cloud technologies without spending too much coin (about $22/month).

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