Wso2 esb soap with encoding file base64 to mailto transport - soap

Question

I have a proxy service who receive an soap message with an encoding base64 file and I try to send an email messsage with an attachment file.
Here is my soap incomming message:
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<soap:Body>
<RetrieveMultipleResponse xmlns="http://schemas.microsoft.com/crm/2007/WebServices">
<RetrieveMultipleResult EntityName="annotation" MoreRecords="0" PagingCookie="">
<BusinessEntities xmlns="http://schemas.microsoft.com/crm/2006/WebServices">
<BusinessEntity xsi:type="q1:annotation" xmlns:q1="http://schemas.microsoft.com/crm/2007/WebServices">
<q1:documentbody>V2ViIFNlcnZpY2UgTWVzc2FnZSBBdHRhY2hlZA0K</q1:documentbody>
</BusinessEntity>
</BusinessEntities>
</RetrieveMultipleResult>
</RetrieveMultipleResponse>
</soap:Body>
</soap:Envelope>
And here is my sequence :
<property name="transport.mail.Format"
value="Attachment"
scope="axis2"
type="STRING"/>
<property name="AttachmentFile"
value="facture.pdf"
scope="axis2"
type="STRING"/>
<property name="messageType"
value="application/octet-stream"
scope="axis2"
type="STRING"/>
<property name="ContentType"
value="application/octet-stream"
scope="axis2"
type="STRING"/>
<property name="Subject"
value="File Received"
scope="transport"
type="STRING"/>
<property name="OUT_ONLY" value="true" scope="default" type="STRING"/>
<property name="STATUS"
value="EXIT_REQUEST"
scope="default"
type="STRING"/>
<payloadFactory media-type="xml">
<format>
<attachment>
<contentID>$1</contentID>
</attachment>
</format>
<args>
<arg xmlns:q1="http://schemas.microsoft.com/crm/2007/WebServices"
evaluator="xml"
expression="//q1:documentbody"/>
</args>
</payloadFactory>
<send>
<endpoint>
<address uri="mailto:exp#domaine.com"/>
</endpoint>
</send>
The email that I receive give me the attach file with the encode text inside.
Thanks for your help,
Best regards,
Nicolas