Please Mr. Postman (https://www.youtube.com/watch?v=dcLbS0yxzdk) TB Shabbat 146

For Rashi and Tosefot interpret the Mishnah on TB Shabbat daf 146 differently. “A person may break a barrel on Shabbat in order to eat dried figs from it, provided he does not intend to make a vessel.” (Sefaria.org translation) Rashi says by ruining (מקלקל) the barrel is not a violation of Shabbat. Tosafot citing a Gemara TB Eruvin daf 34b which prohibits this types of destruction. To solve this contradiction Tosefot distinguish between a good barrel and a poorly made barrel. Our Mishnah is talking about a poorly made and an easily broken barrel.

 This has implications whether one is allowed to open letters and boxes and Shabbat. According to the Mishna Brurah opening letters on Shabbat is forbidden (307:56, 340:41) Most modern poskim follow the Mishna Brurah and rule stringently. Nevertheless, there are sources that would permit opening a letter if the envelope is thrown away immediately. For me it is a question whether open the letter is in the spirit of Shabbat (ברוח שבת). Perhaps it will be wrong to open up a bank statement while permissible to open up a letter from a friend.

 Rabbi Doniel Neustadt writes: “It is permitted to rip off the tape which seals this type of box. But it is forbidden to open such a box if the flaps are glued together tightly and must be separated to open. Corrugated boxes are often reused after their contents are removed, and one is particular to open them in a manner which is not destructive, so that it can be reused. This may be a violation of Tearing. But it is permitted to open a cookie or cereal box or bag, even if one does not immediately empty out its contents and even if the box or bag is not destroyed in the process. It makes no difference if the box is made out of cardboard, plastic or paper, nor does it make a difference if the box contains food or something else such as medicine, clothing or toys. It is only prohibited to open a container which is made of strong, long-lasting material such as a barrel or a corrugated box which might be reused in the future” (https://torah.org/torah-portion/weekly-halacha-5772-beshalach/)