Several features of mojoPortal send email meessages and for these features to work you must configure an SMTP server in 2 places in the Web.Config file.

In the appSettings section you will need to edit these settings:

<add key="SMTPServer" value="localhost" />
<add key="SMTPRequiresAuthentication" value="false" />
<add key="SMTPPort" value="25" />
<add key="SMTPUser" value="UserName" />
<add key="SMTPPassword" value="UPassword" />

In many cases these settings will work if you have an SMTP server running locally on the web server but in other cases your environment will differ and you will need to change these. You can also specify these or any other appSettings in user.config. This can save you from having to re-edit them when upgrading because user.config won't be overwritten.

You also need to specify SMTP settings as the bottom of Web.config in the system.net section:

<system.net>
  <mailSettings>
    <smtp from="noreply@yourdomain.com">
     <network
       host="localhost"
       port="25"
       password=""
       userName=""
     />
   </smtp>
 </mailSettings>
</system.net>

Unfortunately there is no way to put this in an external file so you'll have to update this again any time you upgrade and the web.config file changes.

The system.net settings are needed to support use of some of the built in ASP.NET 2.0 controls like PasswordRecovery whereas the appSettings section has been in use in mojoPortal since before 2.0 ASP.NET came out.