Actually, mail merge does work well for production of a single document, but
the user has to understand the process. I generally create the merge (using
a new merge document based on a template) and find the single record in the
database that I want. Then I print the document. If I want a disk copy, I
have a macro that locks merge fields. An alternative would be to do a query
that would only result in the single record.

I do this for form documents (often drafts that have to be edited) where I
produce the same form for multiple clients, but not at the same time.

I understand that word can be used for multiple letters with differing
address details but in this case I am using it for a single letter each time.
The reason for this is that i want to email the letter... access is virtually
useless for this purpose unless you convert to a pdf. Sometimes you can be
lucky and maintain the formatting by converting to another application but
mostly it's not worthehile.
I can understand what you are saying about this but I'm not sure now how to
complete the merge and save the merged fields. In the second (or third)
posting I left I said I could go to main document setup and make sure normal
word document is selected. Saving after that point actually saves the merged
fields.... but I don't know why it makes a difference, I'm just opening it,
checking that it is normal document and selecting ok, seems to be just
something it makes you do for no reason.