When trying to send an email via Sendmail using the server's IP address to make the SMTP connection (rather than localhost) I get this message in the headers "may be forged" in brackets after the IP address. From what I can see the rDNS is configured correctly:
[root] nslookup ip.ad.dr.es
es.dr.ad.ip.in-addr,arpa name = fqdn.domain.com
[root] dig -t a fqdn.domain.com
fqdn.domain.com IN A ip.ad.dr.es
In /etc/hosts, I have this listed:
127.0.0.1 fqdn.domain.com localhost.localdomain localhost
Should I have fqdn.domain.com against the actual external IP address in .etc/hosts? Or is there a problem elsewhere?