[ADD] mail: res_partner message_bounce

Add the message_bounce field on res.partner. This allows bounced emails to increment
the counter and thus to filter / exclude / archive partners whose email is invalid.

addons/mail/models/res_partner.py

@@ -16,6 +16,7 @@ class Partner(models.Model):
     _mail_flat_thread = False
     _mail_mass_mailing = _('Customers')
 
+    message_bounce = fields.Integer('Bounce', help="Counter of the number of bounced emails for this contact")
     notify_email = fields.Selection([
         ('none', 'Never'),
         ('always', 'All Messages')],

addons/mail/views/res_partner_views.xml

@@ -10,6 +10,7 @@
                 <xpath expr="//field[@name='user_id']" position="after">
                     <field name='notify_email' widget="radio" groups="base.group_no_one"/>
                     <field name="opt_out" string="Mailing Opt-Out" groups="base.group_no_one"/>
+                    <field name="message_bounce" groups="base.group_no_one"/>
                 </xpath>
                 <xpath expr="//sheet" position="after">
                     <div class="oe_chatter">