Sendmail does not work on a host

Hi All,
I'm not an expert in Unix. But, know the basics.

Here, I have two hosts with the same OS (Solaris 5.10)
But, sendmail command works in one host.
When I used the same command from another host, I receive neither mail nor any error.

CMD: echo "Subject:Hi\nGoodDay" | sendmail "Mymailid"

My proto.m4 and .mc files are exactly the same
Are there any other files/details I need to check/verify for?

Please throw some light on this issue.

Thanks,
Siva Parvathi

I haven't used Solaris for some time, but have you compared the sendmail.cf files on the two systems?

One may be spoofing the server name to get around SMTP servers that insist on pinging the source computer, not going to happen behind a firewall.

sendmail.cf is usually in /usr/lib - but search for it if it is not there in Solaris.