ec_header_prefix

ec_header_prefix — prepend to a header in the current message

ec_header_prefix { field-name } { field-body }

This will find the header named and should it exist, prepend the specified newtext to the field body of the header.

You should not use this function in the set_binding phases (regardless of version), and, as of Momentum 2.2.2.37, it will not work in these phases.