Glad you like our service! In the future don't hesitate to reach out to us through support (I work at Lob)! The scuff marks that you saw in your mail are most

Glad you like our service! In the future don't hesitate to reach out to us through support (I work at Lob)! The scuff marks that you saw in your mail are most likely due to belt rollers in the USPS sorting facilities. We've tried a lot of different combinations of paper, ink and protective coatings to minimize the chance of mail pieces being damaged but we haven't found a combination that 100% removes the chance of damage during the USPS sorting process. Throughout the mailing lifecycle a piece of mail will go through several sorting facilities. Each facility has similar sorting machines but they might be in different conditions. There's a chance that a certain sorting facility has machines with more worn out rollers that cause higher damage rates than others. This would manifest in mail pieces going to a certain zip code experiencing higher damage rates. For mail that is returned to the sender it has to go through even more sorting facilities (both when being delivered and back) that causes an even higher damage rate. Here's a video showing you the type of sorting machines each mail piece goes through: https://www.youtube.com/watch?v=gB7QOK1bd3U https://www.youtube.com/watch?v=gB7QOK1bd3U