In most cases, I have seen "Glad to hear it" or "Glad to hear that", which expresses your feelings about smth you have heard or read. Is it ok to write "Glad to hear THIS", responding to some news in a letter received from a penpal? In other words, a person received a letter describing some news and writes in his answering letter: "Glad to hear THIS". Or is it more logical to write "Glad to hear IT/THAT", considering that it was THAT piece of news (or IT) in the received letter? Or is there no difference at all? I am not a native speaker of English. Thank you.