JavaMail uses several licenses:
Most of the JavaMail source code is licensed under the CDDL license and the GPLv2 with Classpath Exception license; see the license information at the top of each source file.
The source code for the demo programs is licensed under the BSD license; again, the license is in each source file.
The binary jar files published to the Maven repository are licensed under the same CDDL and GPLv2+CE licenses as the corresponding source code; see the file
in each jar file.
The JavaMail API specification is licensed under the standard JCP Specification License.
You'll find the text of the CDDL and GPLv2+CE licenses in the workspace in the file
mail/src/main/resources/META-INF/LICENSE.txt. The specification license is in the workspace at
mail/src/main/java/doc-files/speclicense.html. Don't let the presence of these license files in the workspace confuse you into thinking that they apply to all files in the workspace.
You should always read the license file included with every download, and read the license text included in every source file.