There are three general message categories: system, personal, and messages to Naomi. System messages appear automatically and notify players about important events.

There's a special tab for system messages - Union messages. All system messages can be found there, so it's a simple way to keep track of how many points your union has.
The most important system messages are also sent to the union chat and have buttons that provide additional info.

Personal messages include all of your messages, as well as messages of other union members. You can read them all on the tab with the person icon.

Messages from Naomi related to the Guess the Number game are on a separate tab, so nothing distracts you from socializing.

You can always identify what type of message you received by the notification icon on the corresponding tab.