Most of my clients are busy attorneys. They are nice people, but they are busy. We are all polite, but WE ARE ALL BUSY.
If we were talking in person, on the phone, or while using Zoom during an online mediation or meeting, then saying hello, thank you, and other friendly exchanges would be fine. We could end it naturally enough and move on to the next task on our list. No need to say "EOC", which means "end of chain", which translates into "stop sending me email replies because you are taking up my time and I'm a busy attorney with a gazillion more of these emails besides what I have on my desk, in my voice mail and out in my yard!!"