Hello @user224​ ,

Currently, there is no possibility to send a post to the first 100 users from Intercom. 

Workaround: You can track the first 100 users via API (Tag them) or via custom user attribute and use this data to send posts.

From this workaround, you are tracking the first 100 from your end and use Intercom to send post messages. 

You can also request ("Stop sending" when reaching X Users) feature in @Product Wishlist​ Group someone from the Intercom team will catch this.