I can't get this link on mail

 
string url = "http://ingo.com/ActivateUser.aspx";
            string msg1 = "New Registration user,please find your details below:<br/>";
            msg1 += "<br/><b>Username: </b>" + username;
            msg1 += "<br/><b>Password: </b>" + password;
            msg1 += "<br/><b>Your account is not activated,please activate it by clicking here: </b>";
            msg1 += "<br/><b>Account Title:</b><br/>" + "<a href=" + url + "?ActivationID=" + hash + "></a>";
            msg1 += "<br/><br/> ...