ImapClient Client = new ImapClient("imap.gmail.com", 993, "My_UsernamMe",
"My_Password", true, AuthMethod.Login);

MailMessage message = CreateSimpleMailMessage();
uint uid = Client.StoreMessage(message);

Console.WriteLine("The UID of the stored mail message is " + uid);

Client.Dispose();

// ...........

// This creates a simple mail message with a text/plain body and a PNG image
// as a file attachment.
// Consult the MSDN website for more details on the System.Net.Mail.Mailmessage class.
static MailMessage CreateSimpleMailMessage() {
    MailMessage message = new MailMessage();

    message.From = new MailAddress("someone@someplace.com");
    message.To.Add("john.doe@someplace.com");

    message.Subject = "This is just a test!";
    message.Body = "This is the text/plain body. An additional HTML body " +
        "can optionally be attached as an alternate view";

    // Add the attachment.
    Attachment attachment = new Attachment("some_image.png", "image/png");
    attachment.Name = "my_attached_image.png";
    message.Attachments.Add(attachment);

    return message;
}