I am trying to e-mail a client at regaengineering.com, and I am recieveing the following error message sometimes. Can someone look at this domain and tell me what needs to be done. I am trying to email them via a google apps account and it does work sometimes.
"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 5.7.1 Requested action not taken: message refused (state 18)."
Also, on the client site GFI mail essentials is running for spam blocking.