Rebex.EWS.StoreMessage stores messages on exchange server in editable format

Hello
I am trying to put eml messages onto Exchange server, using Rebex.EWS, but messages received are in editable format, like draft messages. Below is the code I use

protected void SendMessage(byte[] emlData){
Rebex.Mail.MailMessage mailMsg = new Rebex.Mail.MailMessage();
mailMsg.Load(emlData);
//I tried to fix it with X-Unsent header, but it didn't work
messageMime.Headers.Add("X-Unsent", "0");
ews.StoreMessage(config.Folder.Id, mailMsg);
}

Thank you