Any application built in DNN needs to have an email going functionality, for example, DNN sends an email to the user registers on the site/ portal. The other example includes, the forum module sends an email to the owner of the threads when a reply has post etc... and it is also necessary for the site host to send Newsletter email to all register user of the site/ application.

Below are the steps to set up SMTP address in your DNN site/ application.

1. Login to the application with host account.

2. Click on "Host Settings" link under “Host” tab.

3. Set the "Host Details" panel as below



The "Host Email" field must be modified as the email address corresponds to your SMTP settings.

4. Set the "SMTP Server Settings" panel as below


I hope this was informative for you.
Thanks
Eliza