Mailing Permits and Indicias Explained

A postal permit allows companies to send mail without putting actual postage on the letter.  Instead, they print an indicia.  The indicia is what appears in place of the stamp that says something like "Postage Paid - First-class Mail".

You can probably find many examples of this by looking through your own mail.  Some have real stamps on them, some have a postage meter amount and date and many more probably have the indicia. 

Below is generally what an indicia looks like: 

When an Indicia or Permit is used, there won't be a date on the mail piece.

True postage stamps get "canceled," usually overprinted by the Postal Service, so the stamp cannot be used again. This process also applies a date the day the post office cancels it.

A postage meter applies postage and generally also applies the mailing date, so this type of postage, like a stamp, displays a mailed date on the face of the letter.