Express Mail Service (EMS) is a safe and efficient way of sending mail in Thailand and to international destinations.
The consulate uses EMS when sending out documents and other mail to the consulate's customers. When sending the mail, the consulate will by the post office be informed of an “item number”, which can be used to track where the letter/package is, and thereby ensure correct delivery of the mail. If requested by the customer, the consulate can inform him/her of the item number, and the customer can use this for tracking the mail.
You can use the web site http://track.thailandpost.co.th/trackinternet/Default.aspx?lang=en# to track where the letter/package is by entering the item number on the front page.