So, let's take this to its furthest reach. I e mail literally hundreds of people a week, some I know, some I have never met.
I pay zero attention to pronoun fuckwittery, as I actually think making the effort to remember someones name is way more important and respectful. And half the time I can't even manage that.
If pronouns are so important, and having people recognise them is so important, a declaration in an email is a very weak signal for people to see and respond to accordingly.
If being really rigorous about recognising peoples chosen pronouns is the aim, then I would suggest a more effective route to achieving this would be to have people declare them on a big fuck off badge, that must be worn and visible at all times.
Also, I would think a big tech investment is needed so if I am e mailing Holly, and her pronouns this week are they/sheep, then my e mails should be automatically changed to reflect that, as this is the lowest risk route to having people feel respected at all times. Which is of course what we are paid to think about during working hours.
Sometimes leaning into the madness can make the crazy come to life.