SMS inbox includes all the messages that you have received. In this particular feature you can view all received SMS from SMS Gateway App, WhatsAPP, mobile, if you don’t want to receive email alert you can unsubscribe from your profile. 

You can use several filters such as, by entering mobile number or by adding some keyword or name to search specific SMS message that you have received. All received SMS messages are saved in your SMS Inbox and does not delete by its own, so you don’t have to worry about its storage capacity.