I think it's acceptable anywhere. I really thought it was short for something like JAWM, so when I googled it, I just assumed it had to be something else. I'm not Catholic though, so I wasn't aware that was a common salutation and doesn't need to have any correlation to what follows. I'm just glad to know what it means now, lol. I always thought it was directly related to the post, so I felt out of the loop :)