Can't find correct formula

Hi all
I'm a newbie on here and I'm wondering if there is a possible formula for what I need to achieve on my spreadsheet. I'm no ExCel Wiz, the most I can do is an IF function, but I get how the formulas work and understand them, I just don't know where to start with this one. a small section of my very large spreadsheet attached.

ExCel Screenshot.jpg
What I WANT: (Columns A and B) If there is a duplicate email address I need each List Title of the duplicate email address to be merged into one cell with comma and space separation (as per columns D and E) and possibly left with just one email address with all of its List Titles...is this possible?
Many thanks,
Lele

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