The message you see is a standard Android notification and it is used as a security feature to prevent fraudulant apps from sending too many SMS messages. And yes - it annoys a lot of people. The standard limit is 30 messages/hour, although it varies according to your vendor/ROM. If you wish to remove that notification completely there are apps on Google Play like SMS Limit Unlock that can do that. They require that you have root access to the device, but if you have (if you don't - just root your device) it's really simple to remove.