Well in this case they are in an unlimited size buffer. Once the blockage is cleared, all messages are delivered at once! I've seen the postal worker doing da

Well in this case they are in an unlimited size buffer. Once the blockage is cleared, all messages are delivered at once! I've seen the postal worker doing daily collections in the lobby and the container they use could probably hold the letter volume for a month or two without issue. Also, to be clear, my office has been there for nearly 15 years. In that time I've known of 4 or 5 blockages. It's actually very reliable.