The camel-mail component currently handle mails with attachments where the mail body is a plain text message. In this case the MIME-Structure looks as follows:
However if the mail is e.g. sent by Outlook and the mail body contains formating and a picture, the resulting multipart structure might look like this
Without the patch, the attachments will be as expected, but the body will be the same as attachment (or some bogus string if the mail does not contain a text attachment).