[ubuntu] fail to send mail by: echo "mail body...." | mail -s "mail header..." <target addr>

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http://ubuntuforums.org – I am trying to send mail using the following command line: echo "message body ....." | mail -s "message header..." name@external_server.com it doesn't work on UBUNTU 12.10 while I used it with no problems on Ubuntu 12.04 . I have the following mail related packages- posrfix, sendmail and mailutils. I appreciate any directions to debug & resolve the problem. (Hardware)