I have published code on GitHub with the following license:
Quantum is a point grid rendering algorithm written in Scala
Copyright (C) 2018 Markus Appel
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, see http://www.gnu.org/licenses/gpl-3.0
I am available for any questions/requests: firstname.lastname@example.org
The layout of this license does not match any "best practices" and tutorials. But I do not like these, mainly because they want me to add multiple lines of legal notice in every file.
For me, that is almost unacceptable.
So, best practices aside, is this a valid license?