Why can I not just double-click to open a CSV file like I do other spreadsheets?

A CSV is a type of Excel Spreadsheet format that is designed to deal with the lowest level of data. This means that special formatting is not supported in this type of spreadsheet. Most notably, CSV spreadsheets will format numbers greater than 15 digits in Scientific Notation. Since Certified Mail article numbers are 20 to 22 digits, this is often a problem when downloading data from your Certified Mail Labels account. 

Anytime you download a file from your Certified Mail Labels account that has a file extension .csv, you will want to follow the steps for importing CSV data PRIOR to opening the file. Double-clicking to open a CSV file will automatically format your Certified Mail article numbers in Scientific Notation which probably will render them useless to you.

If you double click to open a CSV file, and SAVE before you close it, you will have saved those numbers in Scientific Notation and importing data according to the steps above will produce the same Scientific Notated numbers.

Best practices when dealing with CSV data is to download, open a NEW Excel workbook, and import the data according to the instructions found by clicking here. This way you are sure you are not corrupting the numbers.