<?xml version="1.0" encoding="UTF-8"?>
<feature-group-spec name="domain-mail-sockets" xmlns="urn:jboss:galleon:feature-group:1.0">
    <feature spec="domain.socket-binding-group.remote-destination-outbound-socket-binding">
        <param name="remote-destination-outbound-socket-binding" value="mail-smtp"/>
        <param name="host" value="localhost"/>
        <param name="port" value="25"/>
    </feature>
</feature-group-spec>

<?xml version="1.0" encoding="UTF-8"?>
<feature-group-spec name="domain-mail-sockets" xmlns="urn:jboss:galleon:feature-group:1.0">
    <feature spec="domain.socket-binding-group.remote-destination-outbound-socket-binding">
        <param name="remote-destination-outbound-socket-binding" value="mail-smtp"/>
        <param name="host" value="${jboss.mail.server.host:localhost}"/>
        <param name="port" value="${jboss.mail.server.port:25}"/>
    </feature>
</feature-group-spec>

Use the expressions in domain.xml as well
[WFLY-13717] Use the expressions in domain.xml as well
