However when couriermlm runs, EXT still contains its original value, so
couriermlm reads EXT, and will not understand the command.
I don't understand. If I have a .courier-default or a
.courier-anand-default, EXT contains the string "anand-help" in both
cases, so I would expect that couriermlm, when run out of either file,
should work in the same way. I have confirmed this by printing out
the environment variables for delivery under both .courier-default and
.courier-anand-default. The only variable that differs between these 2