Hi, I don't want that my mail is visible to everyone. Not sure if someone can create a script, parse some bug reports and pass all the assigned mail adresses in clear text. However I did receive spam with mail adresses that were not known elsewhere. At least there should be an option to disable public visibility of the own mail adress. This is a data security nightmare.
You're loudly warned about this when signing up: https://bugs.kde.org/createaccount.cgi
This is a limitation of how Bugzilla is designed (intentional or not, email addresses being public are part of how it works), and you are warned during the registration process that this is what will be happening (which is why it recommends you use something other than your primary account)