My personal experience, I spend many hours to set smtp account with no sucess, all forums and help guides with always the same response: Email Test Failed.
Finally, i decided to restore to factory default settings, and reapply smtp config as provided (and all other configs
![Angry >:(](http://forums.dlink.com/Smileys/default/angry.gif)
). Immediately emails test result successfully and alerting begun to work as expected.
Hopes it helps.