probably not going to happen as a built-in core feature.
one of the main reasons web based bulletin boards like phpbb were developed was to replace the old mail list type of scripts that people were using in the old days.
I am an old guy and very old fashioned but even I understand that if you want to be part of a web based bulletin board that you have to be willing to visit that board/website whenever you wish to know what is going on.
it really doesn't take any longer to click on a bookmark to the board and check the list of new posts than it does to check your email and browse through a list of posts etc. for some it is even faster and easier to visit the site and check things out.
I'm baaaaaccckkkk. still doing work on donation basis. PM your needs.
Premium phpBB 3.2 Styles
If a tree falls in the forest and nobody is there, does it make a sound?