FAQ: Excel Data cannot retain the format in Mail Merge?

Issues with Dynamic Data Exchange Option in Excel

Various issues may arise when the Excel option, Ignore other applications that use Dynamic Data Exchange (DDE), is selected.

Workaround: Click the Microsoft Office Button (upper left corner of Excel), and then click Options. In the Advanced category, scroll down to the General options, and then clear the Ignore other applications that use Dynamic Data Exchance (DDE) check box. Restart Excel.