Active users on a messaging application

Here is a table containing information from a P2P messaging application. The table contains send/receive message data for the application's users. The structure is as follows:

Table name: user_messaging

date
sender_id (#id of the message sender)
receiver_id (#id of the message receiver)

Using Python, calculate what fraction of senders sent messages to at least 9 unique people on March 1, 2018.