Mail-merged information takes on the formatting of the merge field in the main document; any formatting you apply in the data-source document is ignored. Format your merge fields in the main document to make merged data appear the way you want. You may also be able to use formatting switches available to Word fields to achieve the formatting you're looking for.
For more information about using field switches to control the appearance of text, dates, and values, see "A Closer Look at Field Formatting," p. 789.
Adjust your Print options?they're probably set to print field codes rather than field results. Choose Tools, Options, and click the Print tab. Then, remove the check from the Field Codes check box in the Include with Document section.
Sometimes you can solve this problem by clicking the Merge button to display the Merge dialog box, and clicking the Don't Print Blank Lines When Data Fields Are Empty option button. If blank lines are appearing where you've used an If, Ask, or Set field, try to insert the field within an existing paragraph, not in its own paragraph. If your document format won't allow this, format the paragraph mark as hidden text.
Then, before you print, make sure that hidden text doesn't print. Choose Tools, Options; click the Print tab; clear the Hidden Text check box; and click OK.
Another way to print text inserted by an If field as a separate paragraph is to insert the paragraph mark directly into the field code that generates the text, surrounded by quotation marks.
For more information about creating and editing field codes manually, see "Placing Fields Directly into a Document," p. 780.