A project ending as abandonware is always a possibility. One reason projects get abandoned is losing funding, which can be secured by using dual licensing and selling some features to businesses.
That is not my point.
Having a CE or OS version and an Enterprise Version can lead to conflict of interest. Do you add a feature to the OS Version or do you spend time on the Enterprise feature? There are a lot of examples, Emby is one, others are escaping me right now.
There are other models that work well like paid support etc. Nonetheless i will stay away.
This has been said over and over again. I have been hosting Mail now for over 2 years and have yet to encounter any problems. Although, i would not recommend to set it up manually and rather advise to use one of the ‘all in one’ suggested solutions here in the thread.