On 13/11/06, Tom Brown <tom at ng23.net> wrote: > Hi > > I need to set some of our boxes to send mail through our smarthost. In > the sendmail.mc file i have set the smarthost and rebuilt the > sendmail.cf file. When i send a mail locally on the box though i get > this error > > Diagnostic-Code: SMTP; 553 5.1.8 <root at localhost.localdomain>... Domain > of sender address root at localhost.localdomain does not exist You can give the host a fully qualified hostname in /etc/hosts or /etc/sysconfig/network and that should resolve the problem. i.e. if the system is 192.168.1.10 then in /etc/hosts have... 192.168.1.10 system system.mydomain.com Then 'service sendmail restart' and you should be good. There are other Sendmail workarounds but this is how we setup systems that aren't mail servers as such. Will.