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For what? Just for bigger anxiety of sender and recipient (both)?
Why anxiety? It is nice to know that other side recived your message..
"Nice" isn't correct word (in my opinion). In 99% of business related communications for me is more important to send message and I don't care, has recipient seen it or not. In my opinion all these "bells and whistles" like the "seen" tag induces more inconvenience than brings "joy". Another point: when one of persons sees tag "Seen", he thinks that he can sent more and more and more and more. And as result workflow magically loses efficiency and goes just a kind of "message wanking". It's one of reasons why I prefer to use CGT site or Trello for my business instead of Whatsup/Viber/whatever. (Because I want and need to work but don't want to be bombed by unimportant messages every second).
"send message and I dont care".. I have to disagree with this. I care that my clients get what they need. And in case there is "seen" message, I would know they got it, this way I'm not sure if they got it or not. I dont mind getting client input while I work, that speeds up my process instead of doing it wrong way and then fixing it.
But, we are all different, so my way maybe wrong for you, and your way to me.. cheers mate!