This morning we couldn't receive email from outside our company's domain (domain.com.au), but we can send email to outside (e.g hotmail, gmail, yahoo). When I tried to send email to my work email address using my gmail account, I received this message
  Technical details of permanent
  failure: Google tried to deliver your
  message, but it was rejected by the
  recipient domain. We recommend
  contacting the other email provider
  for further information about the
  cause of this error. The error that
  the other server returned was: 550 550
  Unable to relay for 
[email protected]
  (state 14).
I tried using telnet to send email, and it works. But still I couldn't figure out why I can't receive email from outside.
I'm not sure if I provided enough info. I'll try to provide as much info as needed to help me solve the problem.
Thanks