in 3.x stability is more important then code-cleanliness
in 4.0 this might be an option. but i must say, i never had a problem with JavaMail. does commons email offer something more then just a convenience layer on top of JavaMail ?
It does offer a ByteArrayDataSource wrapper for InputStreams and other ByteArray attachments.
It also allows takes simple URLs and file locations as attachments and manages pulling in the data. This is more convenience.