I have a few questions on the ruling, answered in the question http://www.yeshiva.org.il/ask/?id=85032 : 1. From where do you take this Psak 2. According to that can I open a letter on Shabbath Kol Tuv
Shalom, Thank you for your question. The ruling that you refer to in the link is based on the rulings in Shmirat Shabat KeHilchatah in line with Rav Shlomo Zalman Orbach zt"l. There is much discussion about opening containers on Shabbat, and this answer reflects one major trend in halacha – though we are well aware of the other more strict opinions. In relation to opening a letter on Shabbat – there are three issues involved. Firstly, receiving the letter that was delivered on Shabbat. This involves question of the Shabbat boundaries (techum Shabbat), eruv, and work of a non-Jew for a Jew. In most cases where the letter is delivered into the mail box it may be bought inside if there is an eruv and therefore no problems of carrying. Next, opening the envelope. The Mishna Brurah (307,56, also 340,41, and Shaaray Tshuvah 307,5) rule that this is forbidden. The work Shmirat Shabbat KeHilchatah (28,6 in the latest version) rules in line with this and forbids a Jew to open the letter. However, see there in the footnotes where he brings sources that perhaps would permit this if the envelope is ripped and then thrown away (similar to the response you linked to about opening containers). It seems to me that the custom is to be strict – but in a case of need one could rely on the letter of the law and open the letter in such a fashion. Lastly, there are restrictions on what one may read on Shabbat. Letters are generally considered as forbidden. The rabbis write about leniencies based on the fact that one may have need of the important information in the letter even on Shabbat. With today's e-mail etc, it seems unlikely that any letter will contain news needed on Shabbat, and therefore it seems that one should refrain from reading the letter on Shabbat. Blessings.