The I-797C Petition Receipt Notice and the I-797B Approval Notice are very important documents for the employer to be able to request worker visas. In May 2016, USCIS announced that if the employer included a prepaid label for the I-797C and the I-797B, they would use UPS mailing vs. USPS standard mailing.
However, there have been several times since the above announcement, including two recent cases, that the employer has received the documents by regular mail instead of UPS. In another case, the employer has received the document by regular mail and again by UPS.
I have attached a UPS Prepaid Label that has not been used by USCIS. The employer received the I-797B via regular mail last week.