I got this text from US embassy AbuDhabi. It is their link on telegram https://t.me/abudhabiiv.
((For our dear applicants from Iran, we appreciate your efforts to come for your visa interviews and sympathize with all the logistical hurdles you are facing to get to Abu Dhabi. Assuming that your visa is approved during your interview, we wanted to clarify how you can get your passport and visa back, as this is a common cause of confusion:
1) Typically, the American consular officer will keep your passport at the end of your interview to issue your visa and send it back to you via Emirates Post before you return to Iran. Usually, it takes around 1 week maximum for the passport to be back in your hands although occasionally we encounter technical problems that may cause slight additional delay. In this case, you would have to stay in the UAE until the passport and visa is returned, and you will need to figure out your logistics, hotel, and flights situation to stay longer in the UAE. We cannot make the visas issued faster if you have a flight back to Iran in 1 or 2 days.
2) Alternatively, you can take your passport back at the end of the interview and return to Iran. Once you are in Iran, you can work with a friend, relative, or agency to send your passport by mail to the US Embassy in Abu Dhabi where it must be received by our embassy via Emirates Post, the postal service of the UAE. We will then issue your visa and mail it back to your friend, relative, or agent in the UAE via Emirates Post to remit it to you. This option may be better if you cannot or do not want to spend additional time in the UAE after your interview.
Please give these options a thought before you arrive, and let the officer know if you would prefer to keep your passport after the interview and send it back once you are in Iran. Otherwise, we will typically keep your passport and send it back once the visa is issued.))