rmail-set-header-1

rmail-set-header-1 is a compiled Lisp function in `rmail.el'.

(rmail-set-header-1 NAME VALUE)

Subroutine of `rmail-set-header'.
Narrow to headers, set header NAME to VALUE, replacing existing if present.
VALUE nil means to remove NAME altogether.

Only changes the first instance of NAME. If VALUE is multi-line,
continuation lines should already be indented. VALUE should not
end in a newline.