Any postal workers on the board? Got a question or two...

What I posted above was from the Rural delivery sectionot of the Domestic Mail Manual. Section 508 2.2.3. Do you have a rural carrier? The same may apply to city routes.
The N'L looks like it was written with the black "China" pencils the USPS uses. As a guess it means no delivery due to length.
Asked a friend, his wife is a carrier. She told me that the station she works from strictly enforces the rules in Handbook M41. She mentioned Section 322. Did some reading and found thisScreenshot_20161207-092909.png
I know it states Parcel Post, the USPS calls all packages Parcels. Guessing this is the first time this happened to you. If so your station may have a new manager. USPS may have noticed all the news reports of packages being stolen and decided to implement the above in an attempt to safeguard your package.