I Keep Hearing I need a Mailer Id, Do I?

As of January 28, 2013, the USPS requires that all mail that receives automation discounts implements the Intelligent Mail Barcode (IMb). The mailer id is important to the USPS, because it enables them to identify who owns the mail. The confusion arises because depending on the mailing scenario in question, the answer of whether you need a mailer id changes. The easiest way to determine whether you need a mailer id of your own, or are okay using your vendor's mailer id is to identify the functional uses that are required with the IMb.