Their best proposed solution is to ban Yahoo email users from mailing lists and encourage them to switch to other ISPs
What the #%^+? Since when is Yahoo an ISP?
Several ISPs outsource their customer email service to Yahoo. If you're with one of those, and especially if you use your ISP provided email address, then moving would fix it (or just move to gmail/outlook.com/whatever, you're mail is in the cloud now anyway, since your ISP moved it there)