Recently I was tasked with writing an email for a wide audience of both mid-managers and technical IT personnel. I needed to explain technically why an event occurred and provide key points to management so they could act upon the information provided. After spending a fair amount of time writing the email, I realized that most managers probably wouldn't read the wall of text and several sections of bullet points I had written. Since I didn't have the option to break the email into two parts (ie.. one technical and an overview) I included a "TL:DR" section titled "TL;DR - Overview" with a paraphrase of the technical information in the rest of the email.
Some team members pointed out that using the phrase "TL;DR" might be considered unprofessional. When pressed about this, none of them could exactly point out why they thought that, but stated that I should probably not use that phrase in the future. Upon further thinking, it might come down to an age disparity. I don't see the phrase "TL;DR" as having negative connotations in any sense. But working with an older generation I could see how some of them might be off-put by the idea that "This email was too long, I didn't read all of it" however true that might be.
Is using "TL;DR" in the workplace (written and oral) unprofessional? If so, why?