Interesting, why reverse?
BLUF: Bottom Line Up Front — e.g., https://hbr.org/2016/11/how-to-write-email-with-military-pre...
For example, during Log4Shell, our Group Director of Operations was helping Support and Account Management with scared customers and was just bouncing customer meeting to meeting. Hence, line one of the mail was "Rollout of mitigation 1 to applications estimated by 12:13; delays expected at only internally reachable middleware". After that, a 3-4 sentence paragraph with more details and then a longer explanation in detail, ideally with keywords highlighted and such. Those would be discussed in some peace later on.