What are these vertical marks on this envelope?

I mailed in my car insurance payment today, and used two 37-cent stamps. I used the envelope which came with the insurance bill, which had a plastic window in it for the return address.

The envelope also had a set of black vertical lines on the top edge, about 2.5 inches away from the upper-right corner. Five of them, covering a one-inch square. The lines were spaced somewhat like this:


||  |  ||

Because the stamps I used were rather oversized, they obscured these lines. If I had used normal-sized stamps, the lines would have been visible.

I assume these things serve some purpose - what is it? Should I be concerned that State Farm will never receive my payment because I’ve interfered with some system of theirs, or the post office?

They are called Facing Identification Marks. Don’t worry, it won’t slow your envelope down by much.

Ah, that makes sense. Thanks a lot.