/etc/exim4/conf.d/transport/ is in exim4-config 4.89-2+deb9u3.
This file is owned by root:root, with mode 0o755.
..
/etc/exim4/conf.d/transport/00_exim4-config_header
/etc/exim4/conf.d/transport/10_exim4-config_transport-macros
/etc/exim4/conf.d/transport/30_exim4-config_address_file
/etc/exim4/conf.d/transport/30_exim4-config_address_pipe
/etc/exim4/conf.d/transport/30_exim4-config_address_reply
/etc/exim4/conf.d/transport/30_exim4-config_mail_spool
/etc/exim4/conf.d/transport/30_exim4-config_maildir_home
/etc/exim4/conf.d/transport/30_exim4-config_maildrop_pipe
/etc/exim4/conf.d/transport/30_exim4-config_procmail_pipe
/etc/exim4/conf.d/transport/30_exim4-config_remote_smtp
/etc/exim4/conf.d/transport/30_exim4-config_remote_smtp_smarthost
/etc/exim4/conf.d/transport/35_exim4-config_address_directory