First, a general model-independent discussion of mesonic correlation functions is given. We derive new inequalities, including one that is stronger than Weingarten's inequality. Then a large set of mesonic correlation functions is calculated in the random instanton liquid model, including diagonal and non-diagonal correlators of udBAR and usBAR type flavored currents, as well as a few of the most important unflavored ones. The results are compared with phenomenological expectations and lattice results. Not only the qualitative behaviour is reproduced in all channels, but in most cases this simple model was found to work with amazing accuracy.