Test if local SMTP server is running
Answer:
To test if a local SMTP server is running, you can try to ping the port 25
# echo -e "quit" | nc localhost 25
220 ubuntu ESMTP Postfix (Ubuntu)
221 2.0.0 Bye
If no SMTP server is listening
# echo -e "quit" | nc localhost 25
localhost.localdomain [127.0.0.1] 25 (?) : Connection refused
