I believe it's a problem in ReflectiveAttachmentRefScanner, the recursion for collections (arrays or lists) is not working, the annotations are searched in the array or list type and not in the contained type. The workaround we have found is to add a wrapper object with a string and the collection, and annotate the string with @XmlMimeType This works because the purpose of this class is to return an AttachmentScanResult object, indicating if there are attachments or not. I don know why it works even returning XOP as the attachment type instead of SWA_REF. I believe it will also work if you change the string object with a DataHandler field annotated with @XmlAttachmentRef Regards, Martin View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4131553#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...