You're getting downvoted to hell, but I'm going to respond anyway. The parent poster here is fully transitioning their gender. They're not cross-dressing at night, they're not "closeted trans"--they're changing their identity for their whole life, in all contexts--personal, professional, etc. Furthermore, they don't want to be known by their old identity anymore--in the parlance, that's called a deadname. So they're informing people of that happening, of who they're identifying as from now on.
It’s often considered professional courtesy to let people know when a property that matters to 99% of humanity (name and gender) changes permanently. Everyone takes a different approach. There are upsides and downsides to the “email autoresponder” method, but it’s certainly an acceptable option in local instances of context.
It turns out, people generally don’t change the terms of address they use for you unless you ask them to!
There are certain predictable exceptions, like when the physical changes reach a threshold of severe mismatch versus your old name and they get uncomfortable and figure it out (or ask :)
Is there any professional context where you wouldn't share when your professional email address changed?
[removed]
"Don't feed egregious comments by replying; flag them instead."