Unable to send email from Msexchange to a sbcglobal.net account

Does anyone have any suggestions with regards to this problem?

MSEXCHANGE Server
Send from Outlook 2003

I have a user with company A and they were unable to send email to a specific sbcglobal.net account. For instance, he can not send email from Jdoe@companyname.com to Jdoe@sbcglobal.net. He is however getting a relay message confirming that the email was received. I have checked his junk mail on sbc account and I was able to send an email from Karl@companyname.com to his Jdoe@sbcglobal.net.

No one else is having an issue sending out emails.

Any suggestions,