After update, when send messages my users receiv this message: This is the mail system at host xxxxxx.ovh.net. > > I'm sorry to have to inform you that your message could not > be delivered to one or more recipients. It's attached below. > > For further assistance, please send mail to postmaster. > > If you do so, please include this problem report. You can > delete your own text from the attached returned message. > > The mail system > > <[email protected] > Name > service error for name=yyyy.com type=A: Host not > found What is hapening?