I'm a firm believer in not LOLing. I got an email today from an external company touting for business. They put LOL in it. Email deleted.
Lol in anything formal is a no no. However, anything else using remote texting, posting on here etc I think use anything that helps to get the correct tone of your message across. It's so easy to read the wrong interpretation into a sentence of simple english.
Malcolm X actually got his name after accidentally sending a "x" at the end of a text message to one of his mates.