You might just have downloaded a message from the server, and found out that it should be saved for later use. This is no problem, the example below shows you how to save the message to the filesystem and later to load it again.

/// <summary>
/// Example showing:
///  - how to save a message to a file
///  - how to load a message from a file at a later point
/// </summary>
/// <param name="message">The message to save and load at a later point</param>
/// <returns>The Message, but loaded from the file system</returns>
public static Message SaveAndLoadFullMessage(Message message)
{
    // FileInfo about the location to save/load message
    FileInfo file = new FileInfo("someFile.eml");

    // Save the full message to some file
    message.Save(file);

    // Now load the message again. This could be done at a later point
    Message loadedMessage = Message.Load(file);

    // use the message again
    return loadedMessage;
}

It is also possible to save a MessagePart, but it is not possible to load it in again.