Problem in adding address at Microsoft Office

Recently, I am examining Microsoft Office 2010 Professional (Beta) and I faced an interesting problem. As soon as replying the e-mail with an attachment, the email is usually "rejected" indicating that the items are not directed. The e-mail address is solved through the global list. But whenever I start the e-mail through the beginning, affixing exactly the same document as well as while using exact solved address, this transmits well.
Anybody who has an idea? Many thanks in advance.
-Schmidt
