Email error message

Has anyone seen this error message before from Outlook? I’m finding a few things on the web, but nothing that explains what this is about or how to fix it.

Your message did not reach some or all of the intended recipients.

Subject: RE: Counsel On Call (w)
Sent: 6/16/2010 10:51 AM

The following recipient(s) could not be reached:

‘Elizabeth Daniel’ on 6/16/2010 10:51 AM
You do not have permission to send to this recipient. For assistance, contact your system administrator.
… H:DBL [internal ip] Connections originating from dynamically assigned IP addresses are not allowed. Please use your ISP’s relay servers.>