Had the same problem. This to me is a bug in DNN. The problem happens in DNN 5.2 but not 5.1.

On the Host Settings page there are two places to set an email address. They are

Host Details
- Host Email

Advanced Settings
- SMTP Server Settings
-- SMTP Username

My SMTP server requires basic authentication with a username and password.

When I click the TEST link next to SMTP Server, if the Host Email does not match the SMTP Username, I get the error message "Thire is a problem with the configuration ...".

If the Host Email matches the SMTP Username the problem does not occur.

This problem only occurs on DNN 5.2 and not on 5.1.

Do not think the Host Email should have to match the SMTP Username. The Host Email should be used as the From Email in messages, but not for signin purposes to the SMTP server.

Thank you,
Andrew

Hi All, I'm not sure if this is still an issue for you. I was getting the same error: "There was an error sending confirmation emails - There is a problem with the configuration of your SMTP Server. Mail was not sent." To fix this problem I entered in the smtp address of 127.0.0.1 I have the dotnetnuke application hosted on a virtual dedicated server, which also hosts my smtp server. By entering the localhost ip address instead of the external ip address to the server and it fixed the problem. Hope this helps!