opnsense-ports/mail/ripmime/pkg-message

You have installed RipMIME, a utility to extract attachments from
MIME-encoded email messages.

If you have an MIME encoded archive (say from sendmail's output)
called recvmail001.mime and you wish to unpack it to a directory
(which already exists) called "/var/tmp/unpack", then you would
type: ripmime -i recvmail001.mime -d /var/tmp/unpack