Sending to dynamic address endpoint - wso2

Question

How can one send an email to a dynamic address?
Address endpoint's URI seem to be static.
Is there a way to inject a property in a address endpoint ?
Here is what I have so far :
<?xml version="1.0" encoding="UTF-8"?>
<sequence name="sendMail" trace="disable" xmlns="http://ws.apache.org/ns/synapse">
<property expression="//email" name="email" scope="default" type="STRING"/>
<log level="custom">
<property expression="fn:concat('Sending mail to - ',get-property('mail'))" name="mail"/>
</log>
<property name="messageType" value="text/html" scope="axis2"/>
<property name="ContentType" value="text/html" scope="axis2"/>
<property name="Subject" value="File Received" scope="transport"/>
<property name="OUT_ONLY" value="true"/>
<send>
<endpoint name="mail2user">
<address uri="mailto:username#gmail.com"/>
</endpoint>
</send>
</sequence>
Thanks.

Answer 1

Define header "To" and use send without endpoint :
<header name="To"expression="fn:concat('mailto:', get-property('senderAddress'))"/>
<property name="OUT_ONLY" value="true"/>
<send/>
Don't forget to define transportSender "mailto" with class "org.apache.axis2.transport.mail.MailTransportSender" in axis2.xml

Answer 2

Here is the final code after jean-michel suggestion :
<?xml version="1.0" encoding="UTF-8"?>
<sequence name="sendMail" trace="disable" xmlns="http://ws.apache.org/ns/synapse">
<property expression="//email" name="mailto" scope="default" type="STRING"/>
<log level="custom">
<property expression="fn:concat('Sending mail to - ',get-property('mailto'))" name="mail"/>
</log>
<property name="messageType" scope="axis2" type="STRING" value="text/html"/>
<property name="ContentType" scope="axis2" type="STRING" value="text/html"/>
<property name="Subject" scope="transport" type="STRING" value="File Received"/>
<property name="OUT_ONLY" scope="default" type="STRING" value="true"/>
<header expression="fn:concat('mailto:', get-property('mailto'))" name="To" scope="default"/>
<property name="OUT_ONLY" scope="default" type="STRING" value="true"/>
<send/>
</sequence>