Self service external mailing list

I apologize if this has been asked already.  I'm having trouble finding out how to word searches and still learning the product.

I work with a small non profit youth group.  We are considering migrating from Google to M365 and everything seems to look good, but I'm missing how to do one thing.

We maintain a small list of external email addresses so that we can send emails to parents.  I'm trying to figure out the best option to do this with Office 365.

Ideally, we would have an email address that several users can email.   We would also really like to be able to have users automatically subscribe and unsubscribe to this list (email addresses may be internal or external).  Preferably, the user would send an email to subscribe or unsubscribe.