De Perguntas freqüentes sobre o recurso de mala direta no Microsoft Word 2003, Word 2007 e Word 2010 :
Q15: Can I add an attachment when performing a merge to an e-mail message?
A15: No, you cannot add an attachment when performing a merge to an e-mail message. Microsoft Office Word doesn’t support this functionality. However, you can add an attachment when performing a merge to an e-mail message programmatically by using CDOSys. You can contact a solution provider to build solution for you.
Existe pelo menos um utilitário gratuito para ajudá-lo - Anexo de Mala Direta do Outlook (observação: nunca usei isso pessoalmente) .
Outlook Mail Merge Attachment supplies the mail merge process in Microsoft Office Word and Outlook with the functionality to add an attachment. The script is tested on Microsoft Office 2003, 2007, 2010 and 2013.*