Player events + mail receive event

src/main/java/emu/grasscutter/server/event/player/PlayerReceiveMailEvent.java

@@ -0,0 +1,24 @@
+package emu.grasscutter.server.event.player;
+
+import emu.grasscutter.game.mail.Mail;
+import emu.grasscutter.game.player.Player;
+import emu.grasscutter.server.event.Cancellable;
+import emu.grasscutter.server.event.types.PlayerEvent;
+
+public final class PlayerReceiveMailEvent extends PlayerEvent implements Cancellable {
+    private Mail message;
+    
+    public PlayerReceiveMailEvent(Player player, Mail message) {
+        super(player);
+        
+        this.message = message;
+    }
+    
+    public void setMessage(Mail message) {
+        this.message = message;
+    }
+    
+    public Mail getMessage() {
+        return this.message;
+    }
+}