“Internal messaging with e-mails” is my default setting for all users. A number of users over the years have specifically requested that their e-mail addresses should not be disclosed and that they wish all contact to be via internal messaging, so I made it my standard approach
I don’t think your standard approach is achieving what you or users think it is, or at least no better than any other option. But I’ll do some testing and summarise the actual behavior of each setting. It’s complex, which is one reason I’d like to simplify it.
Out of interest, how much actual use of internal messaging do you have (messages per day / week / month)?