I am running odoo8 in a virtual machine with ubuntu serve (using proxmox). 

During 2 years the server was in my house running 24/7. Everything was fine. For maintenance and money reasons I have decided to rent a dedicated server in a french hosting provider (OVH).

I have migrated the virtual machine from my personnal server to the provider and everything seems to be ok. Until I realised my mails are not sent anymore ... 

When I test my outgoing mail server with the "connexion test button" it says : (I try to translate)

Connexion failure

Here is what we have instead : -3

Temporary failure in name resolution

My SMTP configuration is OK. I guess it is related to the new dedicated server or the new network configuration (/etc/network/interface) ?

Does anyone have a clue ? I don't even know where to look ?

openerp.log when I test the outgoing mail conf:

2016-05-05 10:02:30,243 970 ERROR production openerp.netsvc: Échec du test de connexion !

Voilà ce que nous avons à la place:

 -3

Temporary failure in name resolution

Traceback (most recent call last):

  File "/opt/openerp/server/openerp/netsvc.py", line 292, in dispatch_rpc

    result = ExportService.getService(service_name).dispatch(method, params)

  File "/opt/openerp/server/openerp/service/web_services.py", line 626, in dispatch

    res = fn(db, uid, *params)

  File "/opt/openerp/server/openerp/osv/osv.py", line 188, in execute_kw

    return self.execute(db, uid, obj, method, *args, **kw or {})

  File "/opt/openerp/server/openerp/osv/osv.py", line 131, in wrapper

    return f(self, dbname, *args, **kwargs)

  File "/opt/openerp/server/openerp/osv/osv.py", line 197, in execute

    res = self.execute_cr(cr, uid, obj, method, *args, **kw)

  File "/opt/openerp/server/openerp/osv/osv.py", line 185, in execute_cr

    return getattr(object, method)(cr, uid, *args, **kw)

  File "/opt/openerp/server/openerp/addons/base/ir/ir_mail_server.py", line 215, in test_smtp_connection

    raise osv.except_osv(_("Connection Test Failed!"), _("Here is what we got instead:\n %s") % tools.ustr(e))

except_osv: (u'\xc9chec du test de connexion !', u'Voil\xe0 ce que nous avons \xe0 la place:\n -3\nTemporary failure in name resolution')

2016-05-05 10:02:30,248 970 INFO production werkzeug: xx.xx.xx.xx - - [05/May/2016 10:02:30] "POST /web/dataset/call_button HTTP/1.1" 200 -