set limit

app/admin/emails.rb

@@ -18,5 +18,4 @@ ActiveAdmin.register Email do
     #   permitted
     # end
     
-  end
-  
+  end

app/controllers/messages_controller.rb

@@ -3,8 +3,12 @@ class MessagesController < ApplicationController
 
 
   def create
-    @message = Message.create(message_params)
-    render json: {}, status: :created
+    if params[:title].length > 300 ||  params[:name].length > 50 || params[:description].length > 1000
+      render json: {}, status: 400
+    else
+      @message = Message.create(message_params)
+      render json: {}, status: :created
+    end    
   end
 
   private