One of our sites stopped sending it’s mail a few days ago. Unfortunately, the SMTP plugin used does not provide any debug logs of the SMTP connection, and it’s ‘test’ tool just says that it sent the mail successfully. The logs for the SMTP service provider suggest they haven’t seen the connection. I issue a new password and reconfigure, still the same symptoms.
So, I just want to do a simple check of the new SMTP creds. I also wanted to use a simple tool to avoid having to recall (Google) the magic SMTP protocol incantations and perform them via ‘telnet’ or whatever. The ‘ssmtp’ tool sprung to mind for some reason, so I figured I’d see how simple that would be to use in this case.
I fired up a disposable docker container to perform this in.
docker run --rm -ti alpine sh
Then, installed and configured ssmtp as follows:
apk -U add ssmtp cat >/etc/ssmtp/ssmtp.conf <<EOF Mailhub=smtp.mailserver.com:587 Hostname=mydomain.com AuthUser=29a0ca06-ec73-488f-883e-f8bda2225a99 AuthPass=29a0ca06-ec73-488f-883e-f8bda2225a99 UseSTARTTLS=YES EOF
Now I can send test mail like this:
echo "Test mail" | ssmtp -v email@example.com
The output will show the SMTP transaction, and ultimately whether or not the authentication was successful.