CRM built for network effects?

Hello— I’m looking for a new CRM and curious if this community has any recommendations.

I have a bit of a unique use case— I’m looking for a CRM to automate the forming of lots of small networks of users. So I’d like people to be able to join new lists, and then receive different emails based on the quantity of users in each list. I’d also like for there to be easy ways for people to create new lists and refer other contacts to join.

Any thoughts? Thanks in advance!