Using your favorite editor, create the following file:
HomeDirectory/.dt/types/dtmail.dt
Enter the following lines into this file:
#
# Override default Print action for mailboxes
#
ACTION Print
{
LABEL Print
ARG_TYPE DTMAIL_FILE
TYPE COMMAND
WINDOW_TYPE NO_STDIO
EXEC_STRING sh -c ' \
dtmailpr -p -f %(File)Arg_1% | mp -m -l | \
dtlp -u %(File)Arg_1%;'
}
dtmailpr is a print filter that strips out attachments, resulting in a stream of plain text. dtlp is the standard CDE interface to lp. %(File)Arg_1% is the file being printed.
Modify the EXEC_STRING to include the print commands you want.
Restart Mailer.