Notice to Packagers regarding Licensing and SSL Bindings

We (the Mutt team) are not lawyers; this notice is intended to alert
package maintainers to potential licensing issues regarding Mutt's
distribution.

* License Overview:

Mutt is licensed under GPLv2 or any later version (GPLv2+). However,
it includes bindings for OpenSSL and LibreSSL.

* Incompatibility with OpenSSL (pre-3.0) and LibreSSL:

According to the Free Software Foundation (FSF), the licenses for
SSLeay, LibreSSL, and OpenSSL (versions prior to 3.0) are incompatible
with the GNU GPL. This is primarily due to "advertising requirements"
that constitute additional restrictions not permitted by the GPL.

It appears Mutt cannot be easily redistributed in binary form when
built with these libraries, unless they are considered "System
Libraries" of the operating system under the terms of the GPL.

* OpenSSL 3.0 and GPLv3:

OpenSSL 3.0 is licensed under the Apache Software License 2.0. The FSF
states that the Apache 2.0 license is compatible with GPLv3, but not
GPLv2.

Since Mutt is GPLv2+, it can be distributed alongside OpenSSL 3.0,
provided the resulting binary is distributed under the terms of the
GPLv3. This utilizes the "any later version" clause of Mutt's license
to resolve the Apache 2.0 compatibility conflict.
