Hi there
I'm not a developer (still a newbie...deployed my first site last year). I tried this mod on 3.8.2 last year, couldn't get it to work (emails kept going round in a loop) and stopped trying when I discovered 4.0 was on the way. Presently I'm in the process of testing out 4.0 with a view to moving my 3.8.4 site to 4.0 soon. Always intended to try again with EMI as I think it's a great idea. Suspect you did a good job with it but couldn't tell....

Possibly my failure to get it to work was my ignorance.
Whilst I'm not a developer I can probably find someone who knows something about parsing emails if that's what the problem is. Question is though, just to break down' what's required, looking at it as a project, what do you think are the key things that would have to be changed to get it to work with 4.0? I know that there's been some criticism of 4.0 but having had a look at it over the last few days I can see it's a better product and despite my own limitations I seem to be able to work it. So that's where I think the future of EMI is.
If I can get some idea of what's required I might be able to go and get some help to fix it.