e-mail sent /505 must be authenticated

‘jrford@bobfordenterprize.info’ on 3/15/2006 3:02 PM
550 must be authenticated
what is a sent two sites differant servers one sent by outlook 2003 sp2 one sent by Microsoft Office Live Basics subscription Your message did not reach some or all of the intended recipients.

Subject: just trying out
Sent: 3/15/2006 3:00 PM

The following recipient(s) could not be reached:

‘bobford@bobfordenterprize.com’ on 3/15/2006 3:00 PM
550 must be authenticated