How can I use an updated version of JavaMail in XPages?

How can I use an updated version of JavaMail in XPages?

I have a XPage application where I use JavaMail in one of my managed
beans. Currently I have added the jar-file
C:\Programme\IBM\Notes\framework\shared\eclipse\plugins\com.ibm.designer.lib.javamail_9.0.0.20130301-1431\lib\mail.jarto
the build-path of the manged bean. This works well. But now I want to use
a newer version of JavaMail as the Domino server uses version 1.3 but I
need version 1.4.x.
I have downloaded the new JavaMail jar-files from Oracle. In Domino
Designer (version 9) I add this jar-file to the new design element "Code /
Jars" and remove the old jar-files from the build path.
My managed bean is still compiling and running as desired, but if I check
the version the bean is using it reports still version 1.3. To check the
version number I use the debug property of JavaMail and it's reporting
version 1.3 to the domino server console.
Is there a way to tell the domino server to use the jar-files in the
application (i.e. the nsf) and not his own? Is there another approach to
update the JavaMail version?