JavaMailでUnsupportedDataTypeException

JavaMail APIを使ってメールを送信しているアプリケーション(Tomcatで稼動)を別サーバに移したところ、

javax.activation.UnsupportedDataTypeException: no object DCH for MIME type text/plain; charset=Shift-JIS

なるエラーが発生。
charsetをいろいろ変えてみるなどしてもうまくいかず、ググったところ、
http://www-106.ibm.com/developerworks/forums/dw_thread.jsp?message=3534771&cat=10&thread=6294&forum=190#3534771

i found the same error when implementing javamail. and found a perfect solution from the Bugzero website :
===================================================
javax.mail.NoSuchProviderException: smtp or
javax.activation.UnsupportedDataTypeException: no object DCH for MIME type text/plain

These error messages are produced by JavaMail and are completely misleading.
The root cause of the error is a mis-matched or a duplicate pair of mail.jar and
activation.jar. Bugzero packaged mail.jar and activation.jar under WEB-INF/lib,
and if your servlet engine have its own pair of jars in its common or shared lib,
problem may arise. A simple solution is to remove one pair of mail.jar and
activation.jar either from Bugzero's WEB-INF/lib directory, or from servlet engine's
common/share lib directory.
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すなわち、mail.jar と activation.jarの整合性がとれていないか、重複していますよ、とのこと。
さっそくアプリケーションのwarファイルに含まれていたmail.jarをはずして、$CATALNA_HOME/common/lib にmail.jarとactivation.jarを入れて解決しました。