If I have 3 same email addresses in same database. According to your answer, opt out is by manggis ID, that means if the same email address just opt –out once, she/he still can receive our eDM, because still has two same email addresses in the database. We all think it’s a big concern.
Not recommend to have the same email address in multiple contact records in the same database at the first place. When import list, it is recommended RiMANGGIS users not to use “create new” when same email address found in the database. Otherwise, the user may hit unexpected issues.