What is the class of mail the IRS uses to return the original documents submitted for an ITIN application?

Question

Did anyone get their passport back from IRS for their ITIN W7 application along with their I-1040? If yes, I'd like to know the mail class they used to return the document. The IRS site says the original document will be returned through "postage paid standard US mail". We did a change of address and I was hoping the mail forwarding would work for the original documents as well. I tried to follow up with the IRS but I'm also trying to learn what might have happened and why the mail didn't forward to my new address. I did receive my ITIN through mail forwarding. I'm hoping that they sent my passport by a mail class that has a tracking ability.

I like to hear from people who received their original document.

Answer 1

According to IRS document (http://www.irs.gov/pub/irs-pdf/iw7.pdf)

Original documents you submit will be returned to you at the mailing address shown on your Form W-7. You do not need to provide a return envelope. Applicants are permitted to include a prepaid Express Mail or courier envelope for faster return delivery of their documents. The IRS will then return the documents in the envelope provided by the applicant.

*emphasis is mine

This would suggest that unless you provide a different mailing option to them, they will return to you via the standard USPS First Class Mail (although probably metered for them).