Honestly, just list out the domains in an Excel file (or google doc) and make separate columns:
One column should read "Contacted" and another should read "Link Removed."
**note: The domain list should come from multiple sources, not just the GWT list. It is incomplete and untrustworthy. Use Open Site Explorers list and maybe even Majestic/ahref or all of the above. Remove duplicates and sort your list and it should be pretty obvious which are the spam links based on anchor text and domain URLs.
Put x's in boxes accordingly.
Then just go ahead and take all of the screenshots of email contacts you have and put them in a folder, zip it up, and attach it to the email.
That's what I would do. Like I said, the more info you can include the better. As much tracking and data as you can possibly overwhelm them with. They may not look through all of it, but it will definitely indicate to them that you have figured out the problem and worked really hard to fix it.
Please keep us posted on how this works. As you may be able to tell this is something I work on often and am very interested in the process and how it works out. I and the whole community would be incredibly pleased if you were able to keep us informed as to how it turned out.
Good luck!