Stack Overflow is huge and varied. Wouldn't it be great if I could just subscribe to a newsletter with a list of my favorite tags? If I love dealing with android, I think it would make sense for my version of the newsletter to focus more on Android questions.
Or, if I sign up for the Apple SE site newsletter, but don't own a Mac, it would be nice if I my newsletter would focus on the part of the site I do follow (i.e., iOS).
So I would like to suggest that the newsletters for each site (optionally) take into account the user's favorited and ignored tags for that site.
I know that you can receive emails about specific filters, but I don't think that's a good solution for users who already receive the newsletter. Most of the questions it highlights cover topics that I have no interest in. It would be much better if I could filter out all the noise and get down to my likely favorites.