How should I package my photos?

“To avoid damage to your deposit due to Capitol Hill security measures, please package the following items in boxes rather than envelopes for mailing to the Copyright Office: … Photographs.”
— U.S. Copyright Office, eCO Online System

“Also please note that CDs/DVDs packaged in standard full-sized jewel boxes are more likely to survive the mail radiation process than those packaged in slim-line cases.”
— U.S. Copyright Office, eCO Online System