When you are uploading a PDF letter for us to print and mail the first step after selecting your file is to approve the letter. If your letter is NOT displayed here, it could be caused by one of the following reasons:
Adobe PDF Version - You'll want to make sure your PDF letter is saved as Adobe 1.4 or newer.
File Name - Be SURE you do not have any punctuation in the file name. Do not use any commas, apostrophes, dashes or any other punctuation or symbols (i.e. # & * ? @ etc.)
It may also be a browser issue. If you're preview shows a little 'x' you may have to click the 'x' to open the preview in a new window. The preview is driven by Google Docs so prevention of the preview box could be caused by third-party plug-ins which do not allow certain displays within the browser.