reject = 501 Sender domain must exist

[apichart]

I'm configuring sendmail to be able to send email to Internet. My local domain has not been registered and got any public IP yet. I'm not able to send the email to outsite. In mail.log, there is an error "ruleset=check_mail, arg1=, relay=sc@domain.com [192.168.9.120], reject=501 Sender domain must exist" It seems my domain cannot be resolved. However, in /etc/hosts. I alredy define domain name as
"192.168.9.120 domain.com hostname"
What else should I check?

[Marcel Boogert_1]

Hi there,

Try the following and reply with the output:

$ sendmail -v your@emailadress.com
Test
.

Regards, MB.

[Muthukumar_5]

It is because of /etc/hosts and hostname resolvation there.

Try to change as,

192.168.9.120 hostname.domain.com hostname

--- /etc/nsswitch.conf ---

hosts: files dns

--------------

Try nslookup hostname.domainname.com now.

And your will work now.