DSN: Service unavailable (sendmail) (linux)

Error

sendmail does not send outbound emails due to the following errors


Unable to qualify my own domain name (HOSTNAME) -- using short name

qAU1XDDZ007482: qAU1XODZ007484: DSN: Service unavailable


Solution


1- Add a proper host name

sudo hostname domain.com



2- Change hosts file ( edit /etc/hosts )

sudo nano /etc/hosts

IP.IP.IP.IP domain.com


3- Restart sendmail

sudo service sendmail restart