exchange 2010 email sending error 550

Hi,

we have received the below error when sending email to hotmail or any external domain, internal email works fine.  

smtp;550-Please turn on SMTP Authentication in your mail client, or login to the 550-IMAP/POP3 server before sending your message.
scenario:

we have one test exchange 2010 server (testexchnage.abc.com) in our environment and work fine internal and external email (but its on desktop machine), so we are planned and installed new exchange 2010 server (exchange.abc.com) in HP DL series server.

steps: first we installed new exchange 2010 server (exchange.abc.com) and removed test exchange 2010 server (testexchnage.abc.com) successfully, from addremove program. do some step but remove success.

please note: test exchnage 2010 not appeared in new exchnage 2010 EMC.

send connect configuration:

hello: abc.com

SMTP: *

smart host: abc.com

please advice.