Generating mail merge reports
Once you have a complete mail merge definition and template file, you can choose between different kinds of mail merge output. We recommend generating a print preview before you actually print or export your mail merge documents.
* 
If the field Preview all documents as one file is set to No and you preview a report in the Reporting dialog box, the reports are displayed as individual documents. Conversely, if Preview all documents as one file is set to Yes, all reports are displayed in a single document.