sendmail fail to send mail

[jim martin]

Hi.. I just installed sendmail in RH Ent and I had
ensure that the sendmail program is running and
outgoing DNS and SMTP is permit to internet. 

But I tried to sendmail outgoing mail to my yahoo
account using the syntax

mail -s "4 test" jimmartin at yahoo.com < /var/test.txt

/var/test.txt is a test file containing test "this is
a test"
 
I got the following bounched back mail in
/var/spool/mail/root.  What's wrong? Is my syntax
wrong? or do I need to change the default sendmail.mc
file to make it works???

   ----- Transcript of session follows -----
... while talking to mx1.mail.yahoo.com.:
>>> MAIL From:<root at rbox> SIZE=318
<<< 501 Syntax error in parameters or arguments
501 5.6.0 Data format error

--j269SoAT011377.1110101330/rbox
Content-Type: message/delivery-status

Reporting-MTA: dns; rbox
Received-From-MTA: DNS; localhost.localdomain
Arrival-Date: Sun, 6 Mar 2005 17:28:48 +0800

Final-Recipient: RFC822; jimmartin at yahoo.com
Action: failed
Status: 5.5.2
Diagnostic-Code: SMTP; 501 Syntax error in parameters
or arguments
Last-Attempt-Date: Sun, 6 Mar 2005 17:28:50 +0800

--j269SoAT011377.1110101330/rbox
Content-Type: message/rfc822

Return-Path: <root at rbox>
Received: from rbox (localhost.localdomain
[127.0.0.1])
        by rbox (8.12.11/8.12.11) with ESMTP id
j269SmAT011375
        for <jimmartin at yahoo.com>; Sun, 6 Mar 2005
17:28:48 +0800
Received: (from root at localhost)
        by rbox (8.12.11/8.12.11/Submit) id
j269SmkO011366
        for jimmartin at yahoo.com; Sun, 6 Mar 2005
17:28:48 +0800
Date: Sun, 6 Mar 2005 17:28:48 +0800
From: root <root at rbox>
Message-Id: <200503060928.j269SmkO011366 at rbox>
To: jimmartin at yahoo.com
Subject: 4 test

this is a test


--j269SoAT011377.1110101330/rbox--