Update /etc/postfix/main.cf and add the name of your outgoing/relaying mailhost as “relayhost”. Ensure that the relay server is accepting your email first.
e.g. if the outgoing relay is mailhost.xyzserver.com sendmail configuration should look like following.
# INTERNET OR INTRANET # The relayhost parameter specifies the default host to send mail to # when no entry is matched in the optional transport(5) table. When # no relayhost is given, mail is routed directly to the destination. # # On an intranet, specify the organizational domain name. If your # internal DNS uses no MX records, specify the name of the intranet # gateway host instead. # # In the case of SMTP, specify a domain, host, host:port, [host]:port, # [address] or [address]:port; the form [host] turns off MX lookups. # # If you're connected via UUCP, see also the default_transport parameter. # #relayhost = $mydomain #relayhost = [gateway.my.domain] #relayhost = [mailserver.isp.tld] #relayhost = uucphost #relayhost = [an.ip.add.ress] relayhost = mailhost.xyzserver.com
After that restart postscript.
service postscript restart
