UPDATE: I tested this on DokuWiki Hogfather with SprintDoc Template, now. My bureaucracy mail action is configured using the SMTP Plugin. And the 'From' field lists the email address of the loggedin user, not mine, when I receive an email.
Well, I found out by looking at the code in
... that the from field is taken from the admin settings for notifications mailfrom in your admin section ⚙.
I filled in the following into the mailfrom input field:
However, if you want to print out the email adress of the loggedin user in the email by template (usemailtemplate), this also works with the placeholder
@MAIL@, as stated in the documentation  . (tested)