I admit that I’m a writing snob, grammarian from hell, witch in the next cubicle—whatever you want to call it. To quote a Facebook group I recently joined, “I judge you when you confuse their and they’re.”
But there are situations where formally correct writing isn’t necessary or even desirable. One example is when you’re talking exclusively to peers. The staff newsletter, written by employees for employees, will come off as stuffy if it refers to “Mr. Fuster’s performance on the field” at the company softball game. A group text to IT staffers under age 25 didn’t ruffle any feathers when it began, “Imma reserve the conf rm for the 3 pm.”
There are two rules to keep in mind when writing informally. First, be appropriate; that “Imma” would look ridiculous to most people over age 30. Second, err on the side of formality, especially if you have a tendency to “joke” using terms that could be considered offensive. A memo addressed to “Hos and Bros,” meant only for members of a tightly knit sales department, got a writer fired when someone forwarded it to the CEO.