For mail merge we need a data file. This data file is used as source to mail merge document. This data file (source file) can be created in different ways. The best in this situation is to create the MS-Excel file.
Create the MS-Excel sheet with Name, Designation, Address and Category columns (any other if you need). Save the file and start MS-Word. Select Tools -> Letters and Mailing -> Mail Merge Wizard from the menu bar. The wizard will start. In the first step select the type of document. In your case select the Envelop and press next. In the second step select the current document and press next. In the third step, select the use an existing list option and browse link. Choose the excel file already created. A window will appear that will show you all the records of the file.
Click the small icon in the category field. All the categories will be shown select any required category. You will the list of addressed related to that category. Press ok and close the wizard pane. Now show the mail merge tool bar and select the insert merge field icon from that tool bar. Insert the required fields, format these fields and its ready for mail merge.
If you want to change the category press the mail merge recipient icon from the tool bar and select the other category by the same method.
Create the MS-Excel sheet with Name, Designation, Address and Category columns (any other if you need). Save the file and start MS-Word. Select Tools -> Letters and Mailing -> Mail Merge Wizard from the menu bar. The wizard will start. In the first step select the type of document. In your case select the Envelop and press next. In the second step select the current document and press next. In the third step, select the use an existing list option and browse link. Choose the excel file already created. A window will appear that will show you all the records of the file.
Click the small icon in the category field. All the categories will be shown select any required category. You will the list of addressed related to that category. Press ok and close the wizard pane. Now show the mail merge tool bar and select the insert merge field icon from that tool bar. Insert the required fields, format these fields and its ready for mail merge.
If you want to change the category press the mail merge recipient icon from the tool bar and select the other category by the same method.