How can you tell a robot from a human if you miss an envelope?

Nostalgic envelopes are distinguished by robots, and people are distinguished by seals and postmarks.

1, seal, if there is handwriting or seal on the old envelope, it is manual processing, because the machine can't complete these tasks.

2, postmark, if the postmark is handwritten, it is manual processing, if the postmark is machine printed, it is robot processing.