All JavaMail implementations contain a Provider Registry that allows other providers to register their protocol implementations with the JavaMail framework. As WebLogic's JavaMail implementation is bundled in the weblogic.jar library, it is not particularly easy to change. If you need support for additional transports or protocols, you should prepend the location of the libraries for the JavaMail implementation to WebLogic's classpath. WebLogic's documentation states that the supplied JavaMail implementation supports only the IMAP and SMTP. We've found that WebLogic also contains Sun's optional support for the POP3 protocol.
You can find additional information on JavaMail and a list of suppliers for various protocol implementations on Sun's web site at http://java.sun.com/products/javamail.
Managing the Web Server
Using JNDI and RMI
Using CMP and EJB QL
Packaging and Deployment
Performance, Monitoring, and Tuning
Logging and Internationalization