Hover over your username in the top right of any page, and select "My Settings" from the drop down
There is a menu strip in the middle which lets you pick "Email".
You can select or deselect various newsletters, and there are options under "Newsletter features" and "Newsletter topics" which let you restrict what content is suggested to you.
If you need finer control, you would need to post a suggestion for the admins:
Bugs and Suggestions[
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