As javamail is a library and not an application itself it should not
have a run-dependency on Java. It doesn't run on its own.
It will always use the java version of the application that uses javamail.
Use source and target arguments compatible with jdk21.
If not using openjdk8 bring back the Java Activation Framework. In
openjdk8 these classes were included in the core packages. In later
JDK versions it was removed again.
PR: 291388
3166f9b4ba