required: inotify-tools
first create this bash script, let’s name it as transport.sh
#!/bin/bash while true; do inotifywait -e modify /etc/postfix/transport postmap hash:/etc/postfix/transport done
make it executable
chmod 755 transport.sh
run the script
./transport.sh > /dev/null 2>&1&
this script will stay on background proccess.
try modify transport file
dd.com smtp:[x.x.x.x]:25 ee.com smtp:[x.x.x.x]:25
save it, and test it
postmap -q ee.com hash:/etc/postfix/transport smtp:[x.x.x.x]:25
enjoy