MyBB Community Forums

Is there a way to hide the memberlist to a certain post count?

it is a group based permission ..
admin panel --> users & groups --> groups --> edit user group --> miscellaneous --> Miscellaneous --> Can view member list?

if you have post number based groups (within the registered group members) then you can restrict freshers to not see members list ..

But how can i set it to only allow them to see the member list after say 20 posts?

You could use group promotions and create a separate group for the users that can view. There is a good tutorial something similar here:

http://community.mybb.com/thread-92069.html