Send email test failture

Hi, someone knows what this error means?

"javax.mail.MessagingException: Can't send command to SMTP host;
nested exception is:
java.net.SocketException: Connection or outbound has closed"

This is when I do a test to send an email.

The mail configuration is ok, and I did the Alarm Notification module's restart.

Why do you think the configuration is OK when you are failing the Send Email Test?

It was working a few weeks ago, but it stopped sending mails. Then, I did a new email configuration and ran a couple of tests, it was working, but again, it has stopped.

It sounds as though the configuration is not OK or you have intermittent IT problems.

You're going to have to provide a lot more information.

Thanks for your advice. Yes, it is an intermitent problem on the email server.
I've done a test with another mail server and it is working again.

Thanks a lot.