Because you will not be connecting, you bear 100% of the risk of a no show on the IB flight. A good chance that if you no show, your IB ticket will be cancelled and will have no value (but check the fare rules for your ticket to be certain). This leaves you in the position of purchasing new IB tickets.
Thus, only you can determine your risk tolerance. Yes, you can make this transfer, including clearing passport control, customs, check-in for IB (bag check), exit and security for IB. But, if your DL flight is late for any reason by a significant amount of time, you are SOL as DL's job is to get you to MAD and IB has no responsibility if you are late.