Must be a US Postal site of some kind...check your browser history to see if you can find the page.
That sounds pretty implausible. The IRS uses first class mail, but there is not any sort of tracking for you to track your refund as it comes to you in the mail.
Maybe you saw that the IRS had sent it? On the IRS website?
I thought I saw a way that you can sign up to see your incoming mail at the post office.
You can preview your incoming mail at the post office.
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Wow---check this out!
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doubt that there is no because the PO would not (should not) know that an envelope contained a refund.
Thanks for all the comments some were very informative. I found the site I had used it was Turboprepaidcard.intuit.com