Found a bug in your code.

[hshamir]

In the AppConfigurations.cs file

1. _domainForApiKey should be _fromName

[ public string FromName
{
get
{
if (!String.IsNullOrEmpty(_fromName))
return _fromName;
else
{

                NameValueCollection appSettings =
                   ConfigurationManager.AppSettings;

                # **_domainForApiKey** = appSettings["FromName"];
                return _fromName;
            }
        }
        set
        {
            _fromName = value;
        }
    }

]

1. _domainForApiKey should be _fromEmail

public string FromEmail
{
get
{
if (!String.IsNullOrEmpty(_fromEmail))
return _fromEmail;
else
{

                NameValueCollection appSettings =
                   ConfigurationManager.AppSettings;

                _domainForApiKey = appSettings["FromEmail"];
                return _fromEmail;
            }
        }
        set
        {
            _fromEmail = value;
        }
    }