Mail Merge Question

I’m trying to do a mail merge via MS Word 2003, which pulls unique values out of MS Excel 2003. Email client = Outlook 2003.

The unique values I am pulling out MS Excel are: Last Name & Document number:

*Dear Mr. [Last Name],

Blah blah [Document Number] blah blah*

This works great for the body, but I also need to insert [document number] in the subject line. I can’t find a way to insert a unique value into the subject line. The data source (in this case MS Excel) in MS Word seems to only map to the body, not the subject line.

Help!