Mechirat Chametz on Internet

Question

I see that many Jewish sites make Mechirat Chametz on the Internet. I know that traditionally, people make the sale by writing a Shtar and using a Kinyan Sudar to make the Rav a Shaliach to sell the Chametz. How does the Qinyan work when somebody only writes his name and address on an Internet site?

I also don't understand why a Qinyan is needed to make the Rav a Shaliach. In several Gemarot we see the concept of "Qanu Miyado", or "Qanu Mineh", e.g. in Sanhedrin, to give the power of a Bet Din which is not regular, or in Baba Batra for Matnat Shchiv Mera. Rashi explains in BB that it's a Qinyan Sudar. The Qinyan Sudar is called Chalipin and we rule that it's made with an Utensil belonging to the purchaser. In the Qetuba, the Chatan makes a Qinyan Sudar for the commitment of the Ketuba. It's not clear to me what is the source that a Qinyan Sudar is needed to appoint a Shaliach, even for Kitvu Utnu Get.

Answer 1

Dovid Grossman was told by R’ Zalman Nechamia Goldberg that although it is preferable, per the Rambam, to make a kinyan sudar when appointing a shaliach, if it is difficult it is not required.

A Teshuva from Dayan Yehoshua Grunwald

March 4, 2021

Contemporary poskim permit a person to appoint a rav to sell his chametz over the phone. (See Mechiras Chametz Kehilchaso 17:11.) This verbal communication is sufficient to make the rav his shaliach (proxy) to sell the chametz. Since the seller is not selling the chametz directly to the rav, no formal kinyan is absolutely required. The rav can write down the details of the chametz—value, location, etc.—as they were reported to him.

One concern with phone authorization is that since no shtar harsha’ah (authorization) is signed, there is no proof of the rav’s appointment, which could possibly invalidate the sale. A remedy would be to additionally sign a shtar harsha’ah and send it to the rav by email or otherwise..

The Chasam Sofer (Shu”t, Even Ha’ezer 1:43) allows authorization of the rav by mail. Doing so online or by email, text message, or the like would seem no different. An electronic communication that leaves a record is superior to a phone call.

Another concern with phone or online appointment of the rav as a shaliach is the absence of the kinyan sudar. Some have suggested that a kinyan sudar be made between the seller and a third party. R’ Dovid Grossman was told by R’ Zalman Nechamia Goldberg that although it is preferable, per the Rambam, to make a kinyan sudar when appointing a shaliach, if it is difficult it is not required.

https://baishavaad.org/qa-from-the-bais-havaad-halacha-hotline-33/

Answer 2

There is no online kinyan - sudar, shtar, mamon, hagbaah, meshiva, vichulu - I see no way how you can do a kinyan online.