Dear John Letters

[Benjamin Barrett]

I've always thought a "Dear John letter" was one from a man to a woman
ending a romantic relationship, and this is confirmed by the Oxford
Dictionary of English.

Here is a citation where it seems to mean a letter written to many people in
a generic letter (from http://www.jat.org/jtt/LipsettBilling.html):

In the process of introducing a new estimating and invoicing system,
however, we had to be careful to not raise the cost of a given job (well,
not visibly, at any rate...). [...]We mailed out a Dear John letter on May
15th, describing what we were doing, and announced that the change would go
into effect on June 1st. We stressed the fact that effective costs would not
change and enclosed the new price list.

Note that no relationship is being terminated whatsoever, it seems to be the
genericness of the word "John" that is being borrowed.

Benjamin Barrett
Baking the World a Better Place
www.hiroki.us