In "What's On Your Servers?" ( http://www.windowsitpro.com/Article/ArticleID/45566/45566.html ), I talked about the software that users run on their Exchange servers (other than Exchange itself, of course). I asked for your feedback about what you're running on your servers and promised to summarize your responses. To briefly recap, I asked you to let me know which categories of software you run (e.g., backup and recovery, antivirus, antispam) and which specific products you use. Thank you for your responses. The results were interesting--and a little surprising. I received several comments and questions about this statement: "Of course, we also have the ever-popular 'forbidden fruit' category, which includes software that Microsoft says you shouldn't install on your Exchange server. This software includes, but isn't limited to, any version of Microsoft Office Outlook, Microsoft SharePoint Portal Server, and Microsoft SQL Server." Several of you wrote to ask why Microsoft makes this recommendation while simultaneously selling Small Business Server (SBS) 2003, which combines several products into one integrated whole. Because Microsoft tests the combination of features in SBS 2003, the company is willing to support those features. But Microsoft can't test every possible combination of Exchange and other products, so the company officially labels those combinations "not supported," even though in many cases (barring resource conflicts) they work together perfectly well. You listed solutions from Sybari, Symantec, and Trend Micro as your most popular antivirus products. Interestingly, several people indicated that they use scanners from multiple vendors at different points in their environments. This layering can provide additional protection at the cost of some administrative complexity and multiple licenses, but for many sites the extra security is well worth it. As for antispam products, your responses indicated a roughly equal split between products that filter spam before it reaches the Exchange server and solutions that run on the Exchange server itself. Two readers use the open-source SpamAssassin toolset, and half a dozen outsource spam protection to third-party services. The rest of the respondents run a variety of products, including Symantec Brightmail Anti-Spam and Sunbelt Software's iHateSpam. Not surprisingly, several readers said that the Microsoft Exchange Intelligent Message Filter is their primary antispam tool; although the tool lacks some of the functionality of commercial tools, its price (it's free) is hard to beat. All the respondents who mentioned backup and recovery software use either Computer Associates or VERITAS products. That's not a big surprise, given the two companies' combined market share. It'll be interesting to see whether the answer to this question changes as iSCSI SANs become more prevalent. In the "everything else" category, readers said that they run a variety of products, including BlackBerry Enterprise Server, fax connectors from GFI and Fenestrae, the Microsoft Public Folders InterOrg Replication Tool for synchronizing public folders and free/busy data, the Exchange Server Best Practices Analyzer, and a host of server administration and management tools. Surprisingly, only a few people mentioned the rate of change in their environments. One administrator told me that he loves his environment's stability, which he attributes in large part to his care in enforcing good configuration-management practices that track changes throughout his Exchange deployment. I suspect that configuration management is the biggest area of potential improvement for most Exchange sites, for two reasons: It's inexpensive to implement, and many shops don't perform even basic configuration management as it applies to Exchange.