What platform do you use for this community list server?

Hi CCGers

Slightly left field question.  I’m looking for a simple email list service where
Anyone can apply to join the list without creating new accounts (so not google groups) 
One or more moderates allow new list members.  They can have any email address
Anyone in the group can post to the group and can see the conversations in the group.

This seems surprisingly hard to find. All my searches come back with email marketing platforms like mail chimp which is a way to broadcast spam not a way for community members to collaborate as peers. I thought google groups would do nicely but, although it allows members to bring their own email address, they still have to create a google account - which is an unreasonable ask for someone that just wants to join a mailing list and not create new accounts on platforms.  

I’m old enough to remember the early days of the web when email list servers were everywhere.  Just like this CCG list manager…. 

Any hints?

steve capell
steve.capell@gmail.com