You may print as much Sample Postage as you like, on either envelope or labels, all at no charge. You should print a Sample Indicium any time you are attempting to print Internet Postage with a new printer, or with a new type of envelope or label. This is especially useful when printing a mass mailing, or when performing a mail merge.
All printers are different, and some print faster than others.
If you have an especially large mailing, you may wish to evaluate the ability of your printer to quickly print postage for all of your recipients. The Print Sample feature merely allows you to make sure your printer is set up correctly, and that your label or envelope is correctly oriented. You may also wish to use the Print Sample feature to print a preview of your finished mail piece. You can use the Print Sample feature as often as you like to test your printer setup, or preview your mail. This Sample Indicium should have printed with the word VOID across the bar-coded area, and is only used as a printer test.