Seems like I hit this mess of an issue too.
(I’ve mentioned it here:
and here
Group mail only display on system admin users. Not on the regular users. 
Is there a compiled step by step guide over how to fix this available?
All this code spread all over posts in this thread makes it quite messy to figure it out (I don´t mean that in disrespectful way. The job done is really fantastic!), but it for me and other users it might make it bit complicated to apply this fix to the system.
(It seems like a bit a pain also because once you make these changes you will have to re-add them on each update, right?)
Out of sheer my own curiosity
How come the SuiteCRM team/ Sales Agility team has not fixed this in the updates and added the code that fixes this bug/problem? 