It means they ran out of time that day and the package has gone back to the post office and you will get your package the next day. I had this issue with several packages and finally found out this information from a mail carrier. Hope this helps
"Delivered to agent" means, someone has picked up mail at the post office for, say a UPS Store. Now, keep in consideration that the Post Office may say that it has been delivered, it may also mean that it is "Ready for pick" up for said Agent.
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