Microsoft's Outlook 2003 has been the defacto standard for business-level communications for several years, especially for businesses that use Microsoft's Exchange system (which is most of them). For anyone using a Mac the options were limited to either basic IMAP access, which doesn't support all of the stored address books, calendars, etc, or Microsoft's Entourage application which is promoted as a reasonable equivalent. There are two key problems with Entourage, however:

1. It doesn't support many of the "Public folder" data sharing mechanisms, so you can't use shared calendars, tasks, etc that are stored in Public Folders, only messages.
2. It is unstable:
   • I can fairly consistently crash it just by writing a message and hitting down down arrow (!)
   • it randomly gets the server connection messed up - you leave it running overnight, come back in the next morning to see "unable to connect to the server", at which point it fails to connect to the server no matter what you do, and requires a magical combination of star alignment and crossing of limbs to get it working again.

A new option entered the arena lately - directly running Outlook using Codeweaver's Crossover Mac application, which provides an emulation layer to run some Windows software directly on your Intel-based Mac (or Linux box). With the brand new release of Crossover Mac (comparable to Crossover Office version 6 for Linux) they finally added official support for Microsoft Office 2003 including Outlook 2003, so at work when my Entourage decided to implode I politely asked for it to be bought for me. Half an hour later I was sitting down to install it.
Crossover Mac has the potential to be a really great program, it is just currently hampered by a few issues:

• Lack of specific documentation. Several people on their forums say that they have Outlook running without any problems but nobody has said exactly what release they're using, exactly what extras were used (you need IE6 installed for it to work fully), what the installation options were for the software, etc.
• Instability. CXMac has locked up on me a few times when it was attempting to "reboot" (not a physical reboot, it's all within the emulation layer).

After wasting half a day on it I still don't have Outlook 2003 running correctly: one install stopped working after I installed IE6, one refused to start Outlook at all, on another I installed IE6 first only to have Outlook not display HTML emails at all (but it is at least running my mailing list filters to keep my inbox clean).
Tomorrow I'm going to try out Outlook XP/2002, to see if it is any more reliable, but so far I'm rather disappointed.