You may wish to delete or add fields types to your mail merge document.
You can do that easily. Just click the Customize Columns button. The Customize Columns dialog box opens. Then, click Add, Delete or Rename to alter the field types. You can also use the Move Up and Move Down buttons to rearrange the order of the fields. When you're done, click OK.
Once you've added all your recipients, click OK on the New Address List dialog box. Name the data source and click Save.