When youre preparing a mail merge, it is recommended that you insert any punctuation in the main document rather than including it in the data source. This is quite logical for several reasons:
1. You wont inadvertently omit punctuation
2. The punctuation will be correct for the context
3. It will save you a little bit of typing when you enter data
4. You will be able to use one merge field in more than one place in your document
Of course, this rule of thumb isnt failsafe. Sometimes the punctuation you use will be contingent upon the data contained in a field or several fields for a specific record.
The solution is simple: if you know you will need different punctuation for some records and the frequency of the need is great enough to warrant it, simply leave the punctuation out of the main document and create a field for punctuation in your data source.
Note: This is another reason why many people prefer using Excel for mail merge processes it is easy to create fields and fill them in quickly with the fill tool.
