While it does sound suspicious to me, you'd have to inquire with the IRS directly about that, or perhaps with your local post office (USPS, not UPS). The IRS phone number is 1-800-829-1040.  I'm surprised you allowed them to send it to an address not on the IRS website. Hopefully, you don't regret this in the future.

Hi, did you get your tax return finally? My tax return documents were also mailed to

Internal Revenue Service,

Austin, TX 73344

by UPS.

I also do not know whether this address is right.

Thanks.

There are several IRS buildings in Austin. See Where To File - Internal Revenue Service for address depending on circumstances.

Always track your mail to the IRS to guarantee a safe delivery.

@liu10435

Thanks. I know I should mail to 

Internal Revenue Service,
Austin, TX 73301

However, the UPS employee said that when he enters this zip code on their computer system it changes automatically to 73344. The UPS employee said this address is OK for delivery. 

It has been 2 months since I mailed, and I have not receive my tax return and there is no change for tax return status online. So I wonder whether this address can deal with my tax return.

I had this happen to me as well. I sent the return on May 2. It’s now Aug 6, and nothing. The “check your refund” site doesn’t recognize the correct info. 

Did you ever get confirmation that the IRS received it? Is this resolved? I’m afraid my return has been lost. (UPS does show it as delivered, but there was a hold up of a couple days while they did some kind of address change.)

I mailed it again with usps (with a note explaining this). And I received my tax return.

@LBinNJ did you end up getting your return processed by the 73344 postal code? I just had the same problem where the UPS store forcibly changed my postal code. By the time I noticed it was already too late: the package was already shipped. Should I send another package or wait and see if it gets processed?

So I mailed a second one to the correct zip code. Finally got a response ( I had some corrections ), I returned it in January, and am still waiting. I’m probably going to send in the return a third time. No idea what happened with the first return sent to the wrong zip code.