Enterprise Mail/Collaboration Requirements

Hi folks,

Complements of our own Greg Shipley, Ron Anderson, and Lori MacVittie, I've compiled a short list of requirements and products our editors have considered for their own lab and production networks.

To find favor with our editors, an enterprise collaboration tool must:

• It must have a robust group calendar/scheduling solution
• It must allow some users to use other e-mail systems
• It must have the option of supporting web clients for calendaring,
  as not all of our staff runs Win32, and we have no plans on migrating
  non-Win32 users.
• It must have a usable interface
• It should not require MS IIS, as we've had enough security problems with
  IIS already.
• It should have PDA sync abilities
• It must be a product that wasn't coded poorly (back to the security
  problem). We'd prefer something that not only has security features,
  but something that was DESIGNED to be secure.
• It should be cost-effective for small organizations
• Not requiring Win32 as a hosting platform would be nice (Linux would be
  ideal)
• It must not suck.

And here are some of the products our editors are considering or using

• Stalker Software communiGate Pro -- in use in our Syracuse, NY lab
• Gordano Messaging Suite
• Convea Convea 5.0
• Sareen Software OfficeTalk

We'd like to hear from you. Given the above requirements, which messaging/collaboration solution would you recommend?