I know this doesn't make sense, but this is the situation:
1) We're using Office 2010
2) We have an in-house Exchange 2003 server
3) We are a small company (50 people)
4) I am the IT department
Here is the problem:
One user cannot send email to one particular external email address. She gets immediate rejection notifications. Here is the copy of the text from the message (email addy changed for privacy):
MAILTO:user@xyz.com on 10/9/2012 1:47PM
The message could not be delivered because the recipient's destination email system is unknown or invalid. Please check the address and try again, or contact your system administrator to verify connectivity to the email sysetm of the recipient. <mail.ourdomain.com #5.1.2>
Now before you go asking me to verify the email addy is correct, YES, it IS correct. I can copy and past the email addy and send to the same addy from any other computer in our office. Just this one computer is having the problem. YES, I have checked for viruses. The rejection email comes immediately as if it were an internal email. I am stumped.