message-qmail-inject-args

message-qmail-inject-args is a variable defined in `message.el'.
Its value is

nil

Documentation:
Arguments passed to qmail-inject programs.
This should be a list of strings, one string for each argument.
It may also be a function.

For e.g., if you wish to set the envelope sender address so that bounces
go to the right place or to deal with listserv's usage of that address, you
might set this variable to '("-f" "you@some.where").

You can customize this variable.