url-bug-address

url-bug-address is a variable defined in `url-vars.el'.
Its value is

"bug-gnu-emacs@gnu.org"

• This variable is an alias for `report-emacs-bug-address'.
• This variable is obsolete since 24.5;
  use `report-emacs-bug-address' instead.

Documentation:
Address of mailing list for GNU Emacs bugs.

You can customize this variable.