I have configured sSMTP on Ubuntu and it worked fine yesterday. But today when I am trying to send email it shows "ssmtp: Cannot open smtp.gmail.com:587" error message.
$ apt-get install ssmtp
$ vi /etc/ssmtp/ssmtp.conf
root=sender.email@gmail.com
mailhub=smtp.gmail.com:587
rewriteDomain=
hostname=mycomputerName
UseTLS=YES
UseSTARTTLS=YES
AuthMethod=LOGIN
AuthUser=sender.email@gmail.com
AuthPass=sender.email.password
FromLineOverride=YES
$ chmod 640 /etc/ssmtp/ssmtp.conf
$ ssmtp username@gmail.com
Hi
Ctrl+D
ssmtp: Cannot open smtp.gmail.com:587
Additional info: Yesterday I used public IP, today I am using private IP. I think it is not any problem.