social/mail_restrict_follower_selection/data/ir_config_parameter.xml

<?xml version="1.0" encoding="UTF-8"?>
<openerp>
    <data noupdate="1">
        <record id="parameter_domain" model="ir.config_parameter">
            <field name="key">mail_restrict_follower_selection.domain</field>
            <field name="value">[('customer', '=', True)]</field>
        </record>
    </data>
</openerp>