Email failed code 110061

I received this error
unable to send notification email because of 110061

What is this error?

Note, I am unable to get a sucessful test email to send from the computer that gernerated this error at the end of the backup, but I can get a test email to send when I input the exact same information using a different computer.


It looks like the email server refused the connection.
There are some issues with emailing in 2.2 version.

They will be fixed in the next release.