private static void SendMessageAndValidateContent(int attachmentSize)
{
var body = RandomStringGenerator.RandomString(attachmentSize);
var attachmentToSend = body.ToAttachment();
var commandHandler = SendMessageWithAttachment(attachmentToSend);
var message = MimeMessage.Load(commandHandler.Body);
var attachmentStream = new MemoryStream();
var receivedAttachment = (MimePart)message.Attachments.First();
receivedAttachment.ContentObject.DecodeTo(attachmentStream);
var bodyInReceivedAttachment = Encoding.ASCII.GetString(attachmentStream.ToArray());
Assert.AreEqual(body.ToString(), bodyInReceivedAttachment);
}