I'm having a similar problem.
I have setup the email alerts, but when I try testing it says "Unknown error" "Alert cannot be sent".
The weird thing about this is the same settings used on a client and not the ADNM work fine, and the they work in the server client too. Test email goes through fine I seem to only get the error in the ADNM tool.
I put in a ticket, but it was closed with no response. I'm testing this program as a possible replacement for my business.
Regards,
Frank