I have a very large list that includes department names that I want to
merge each department's letters into a separate file. Thus, each
merged department document could be emailed separately. The question
is how can I merge the document and have the merge saved to a new file
each time the department name changes? Ideally, I would like the file
name to be based on the department name.

I've done work with macros similar to this before, but it's been years
and I'm a bit rusty.