But business writing is business writing, it’s its own animal with a whole set of protocols. It’s not grammatical, it’s more like MLA citations not being “grammar” but important?
Like, legal pleadings (yes, that’s what they are called LOL) conclude with a “Prayer for Relief,” and a standard prayer is usually like:
“Defendant prays that this suit so wrongfully brought be dismissed at Plaintiff’s costs and for whatever other relief that this court seems just.”
More modern versions are “Defendant requests that this suit be dismissed at Plaintiff’s cost and for other just relief that that court deems applicable.”
Really, legal language is probably THE most formal in so many ways, I can’t even continue without drifting this thread; you spend a minimum of three semesters learning how to do proper Blue Book citations so a Judge doesn’t throw out your suit.
BUT yes you can use “Hey Joe” if it is appropriate in a certain context ... I use “Hey” sometimes with certain contacts with whom I have a pretty close and informal relationship.