Customize registration email

I have modified the email template files for new user creation [1] and resetting the password [2].
[1] /home/frappe/frappe-bench/apps/frappe/frappe/templates/emails/new_user.html
[2] /home/frappe/frappe-bench/apps/frappe/frappe/templates/emails/password_reset.html

However the final output should be modified even further, specially the lines with link to complete registration/password reset.
[1] a href="{{ link }}">{{ (“Complete Registration”) }}
[2] a href="{{ link }}">Reset your password

Now the link points to a server in local network (192.168.x.x) and when users click the link, for example at home, they can’t complete the process.
I’ve tried to use the automatically generated token
/update-password?key=xXyYzZ1xXyYzZ2etc
with the public address and it works. Though most of the users won’t be satisfied with a broken link (even if it would be possible to hack the right result out of it)

Where do I find the controller code responsible for sending the emails so I could change some details and fork it to use the static (and public) name.

I am interesting, how to do we can edit these templates?