Thanks SoZo! The people who will be updating it are barely comfortable just updating a page in their current CMS. Trying to teach them how to make a new post might make their heads explode. Also the nature of the content makes me not really want to archive the newsletters for future searchability. For child protection reasons, once the content has expired, ideally we want it gone.
However, I like your suggestion of the newsletter plugin. I didn't really even think of that. That's probably even better than hosting the newsletter on the site in the first place!
Thanks so much!