The mbox viewer source code created by authors of the mbox viewer project is licensed under 
GNU AFFERO GENERAL PUBLIC LICENSE version 3 which permits free use of the code by individuals 
and organizations. Small portion of the source code is from Code Project site and licensed under 
the Code Project Open License (CPOL) 1.02 which permits, as we understand, free use 
of the that code except in a few unusual cases such as for example the immoral usage.

The mbox viewer executable doesn't link any non-free usage library and therefore it can be 
freely used, as we understand, by individuals and organizations.

The mbox viewer software 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.

Please check the below links for the detailed information on GPL and CPOL license terms.

https://www.gnu.org/licenses/agpl-3.0.txt

https://www.codeproject.com/info/cpol10.aspx

Links to additional publications that can be usefull.

https://www.codeproject.com/info/Licenses.aspx
https://opensource.guide/legal/#which-open-source-license-is-appropriate-for-my-project