I don't believe the law has ever been revoked that requires anyone sending documents through a non-USPS service* to include the appropriate USPS postage cancelled with a pen along with their shipment
* excepting a point-to-point courier service for some reason
The USPS carved out a few exceptions, like delivering urgent mail. Gaming the system will get you raided by armed agents of the enforcement arm of the USPS.
I don't believe the law has ever been revoked that requires anyone sending documents through a non-USPS service* to include the appropriate USPS postage cancelled with a pen along with their shipment
* excepting a point-to-point courier service for some reason
The USPS carved out a few exceptions, like delivering urgent mail. Gaming the system will get you raided by armed agents of the enforcement arm of the USPS.