sendmail only sends emails to its own domain

UNIX AIX
1

Hi, folks!

I have a problem with an AIX 5.3 server running sendmail where
it is able to send messages within its own domain just fine. This
is being used for a web email service portion of a web site. However,
when it attempts to send email to any other domain -- i.e.,
hotmail.com -- it is always rejected.

Here is a log of a given rejected email:

Jan 22 11:08:25 hostname mail:info sendmail[71554]: m0MI8Pgb071554: from=<mailprogram@xxx.com>, size=377, class=0, nrcpts=1, msgid=<672952891.1201025305084.JavaMail.root@mail.server.xxx.com>, proto=ESMTP, daemon=MTA, relay=mail.server.xxx.com [9.17.233.106]
Jan 22 11:08:25 kpnatsp6 mail:info sendmail[152688]: m0MI8Pgb071554: to=<jjwood64@hotmail.com>, delay=00:00:00, xdelay=00:00:00, mailer=esmtp, pri=120377, relay=mx3.hotmail.com. [665.54.245.72], dsn=4.0.0, stat=Deferred: Connection refused by %smx3.hotmail.com.

What do I need to change in my sendmail.cf file in order to allow me to send email to other domains which I specify? Any help would be great, and thank you kindly in advance.

2

It says

"relay=mail.server.xxx.com" in the message. Could it be that xxx.com, whatever the domainname really is, is blacklisted as an open relay?

3

hotmail's server may be refusing connections because of lack of HELO statement, lack of SPF record, lack of rDNS record - there may be many reasons, do a raw telnet session and see what it says.
Is this really an IBM IP address or ADSL ? Hotmail doesn't like adsl pools.

4

The "xxx.com" is something I inserted just for confidentiality's sake.
I'll be trying some tests today, but note that all email from this
box sent externally gets rejected (so it's not just hotmail!)

Essentially, the mail server was (properly) set up not to be an open relay.
I generally want to be able to push email to specified domains.