To be perfectly clear, when I mention trying to talk people away from Outlook and them being resistant, I'm talking about IT people and management, not the common workers, who mostly all hate Outlook.
Agreed. Those who would love a replacement really have very little say in the matter. That's what anyone selling enterprise-y software has to deal with. You're usually selling to the people who won't be using it. This changes the conversation quite a bit regarding the benefits you emphasize about your offering. For instance, you may have to show a higher-up that they can save time/money by using your software rather than telling them they're employees will enjoy using it more because that high-up won't rightfully care.