The CxfRsProducer needs to find a converter to take the String body of an exchange message and turn it into an Object. However when camel-mail is present in the classpath the converter search method picks:
com.sun.mail.imap.SortTerm org.apache.camel.component.mail.MailConverters.toSortTerm(String msg)
This causes the CxfRsProducer to bomb on a NoSuchMethodException.
If camel-mail is removed, the CxfRsProducer client works, finding the right String -> Object converter.