Is there a way to tell maildrop to preserve the existing environment when called from a .forward?

My testing shows that maildrop loses several environment variables (such as RECIPIENT and SENDER) set by the MTA which I need preserved.

Something like procmail's `-p' option is exactly what I'm looking for: (from procmail(1))

-p Preserve any old environment. Normally procmail clears the environment upon startup, except for the value of TZ. However, in any case: any default values will override any preexisting environment variables, i.e., procmail will not pay any attention to any predefined environment variables, it will happily overwrite them with its own defaults. For the list of environment variables that procmail will preset see the procmailrc(5) man page. If both -p and -m are specified, the list of preset environment variables shrinks to just: LOGNAME, HOME, SHELL, ORGMAIL and MAILDIR.

Thanks.