Since mail merge is not among the most commonly used MS Word features, some users might not know how to do a mail merge in Word to create letters, labels, and envelopes. After the field name and before the end curly bracket add a space and the string “dd/MM/yy” Mail merge is a Microsoft Word feature that helps you streamline creating personalized letters, labels, envelopes, emails, and a directory.Your field will now appear like this where Date is the name of your filed (column heading in Excel).At step 4 “Write you letter” right-click you date field and select “Toggle Field Codes”.