[p_l]

I do wonder of is partially not caused by the fact that underneath, Outlook and Exchange aren't massively using SMTP or MIME, they use MAPI which is built around X.400 even if it's no longer available to run Exchange work external X.400 connectivity.

Take that background, and how MAPI essentially prioritises internal email capabilities, and slowly a perfect storm for creation of such misfeatures emerges.

Internally to a corporation, in Outlook/MAPI/Exchange way richer world, implementing such a feature is both simple and possibly easy more useful (less annoying emails to write when you want to just give a short reaction).

But then you hit two confounding factors - systems outside of corporate Exchange server - so instead of using a richer messaging feature you make it into extra text message - and systemd outside the corporate, where your message now leaks out.

This way you can start with reasonably well thought out user story, and end with crap like the way reactions work - and weird extra headers

[mgkimsal]

2001(?) I got an email from a client and it said "Debbie would like to revoke the earlier email". Might not have said 'revoke' but something like that. And there were a lot of extra headers I hadn't seen before. After some questioning, I got that they'd just installed some Exchange server setup (or whatever the direct predecessor was?) and you could undo email. But the 'undo' was to send an email revoking the earlier one. MAPI/internal clients understood it; to external clients like me, it was just another email. I'm not sure they (the client) quite understood that they couldn't 'undo' emails to me, because they could do it just fine to everyone else (inside the company).