Making it easy to email potentially thousands of people at will seems like a bad idea… even if it were on a PM level it seems like it would be too easy to abuse.
Maybe… just pin a topic and assume active users will see it? If it’s a status/announcement thing it’s probably safe to assume they don’t care unless they frequent the forum anyway
A plugin allowing users to opt-in to a newsletter controlled by a mailing service (Mailchimp, Constant Contact) while creating an account on Discourse wouldn’t be too complicated… and seems like it would be a much better way to handle the newsletter usecase.