I’m sure this isn’t about difficulty, as the option to choose between the previous behavior or the currently preferred behavior existed initially but was dropped, presumably to force the issue in his ongoing quest to force MSPs to adhere fully to published standards, which state that email sent his preferred way should be acceptable.
This kind of thing is not new. M$ did it with the constant UAC prompts added in Vista to annoy customers into annoying software vendors to adhere to published standards, which stated that software for Windows should not need administrative access to the machine to perform daily work. Up until Vista, nothing enforced that, and since most accounts had unrestricted admin access all the time, there were few problems caused by deviating from it, so vendors largely ignored it. M$ was successful both in causing huge disruptions to their user base and also in getting the software industry to write better code, allowing for much better overall security.
The issue here is that K9 is not Windows, and its dev is not M$. His campaign is not going to accomplish anything beyond ensuring that a segment of the potential user base is permanently unable to use his product, and that’s a crying shame, because it’s otherwise the very best that there is, IMO.