/// <summary> /// Sends an instant message to the specified subscriber. /// </summary> /// <param name="messageInfo">The message info.</param> /// <param name="subscriber">The subscriber.</param> /// <returns>The result of the sending operation.</returns> public override SendResult SendMessage(IMessageInfo messageInfo, ISubscriberRequest subscriber) { throw new NotSupportedException("The SendGrid sender does not support sending a single email."); }