I have just confirmed from the mail room that any mailings sent here in a manila envelope instead of white will be returned, even if it is certified and/or priority mail.
We don’t get any paper physically touched by our contacts as they copy everything and hand us the copies. It wouldn’t bother me as much if the prison at least notified you that they had rejected your mail, as they did at USP Hazelton. But here, they don’t let you know they rejected anything. I was only notified by tracking numbers that it was going back to my family. Now my family is sending me the same three-page document they previously sent three times priority mail. This is the fourth attempt!
I guess that boils down to the lack of staff here. I can only guess that since there is so much K2, they feel it is more likely that a non-white envelope will be coated in chemicals than a white one.