By: Rabbi Ari Enkin
It goes without saying that according to halacha, it is strictly forbidden to reveal the secrets of others. In fact, in addition to the basic prohibition against lying, which one transgresses when breaking a promise not to reveal a secret, doing so is also a violation of the Torah’s prohibition of “smiting one’s neighbor in secret”  King Solomon teaches us that “talebearers reveal the secrets of others but the faithful protect them”. The prohibition against revealing the secrets of others applies equally to everyone – especially to rabbis and other trusted officials. Revealing the private affairs of another person is so severe that the Talmud notes that Rav Ami expelled a student from his Yeshiva for having revealed confidential information that was entrusted to him twenty-two years earlier! One must be careful to avoid any social settings which might force one to reveal or even hear the private affairs of other people.
Of course, repeating the secrets of others also falls under the umbrella of lashon hara and is in fact one the most severe forms of lashon hara. It is interesting to note that according to halacha, one is to assume that anything one is told is to be kept secret unless specifically instructed otherwise. Much ink has been spilled on how lashon hara, especially exposing the secrets of others, has the potential to destroy friendships. It makes no difference whether one was told the secret in private or in the context of a larger group. One is obligated to keep a secret even in a situation wherein none of the rules of lashon hara would be transgressed by revealing it.
There are, of course, a number of exceptions in which revealing a secret is permitted, and often required. For example, a doctor who has information about a patient whose condition is likely to put the public at risk is permitted to notify the appropriate authorities. In fact, a doctor or other trusted official who withholds such information may be guilty of the Biblical prohibition of “standing idly by your neighbor’s blood.” There are also limited circumstances where one is permitted to reveal the secret of another to save someone from financial loss. Similarly, in certain situations, it is permitted to reveal sensitive information which might be vital regarding a shidduch in order for the parties involved to make an informed decision. It is also often permitted to reveal information to an employer regarding a prospective employee’s dishonesty or unreliability. Even when it is permitted to reveal the secrets of another person, one must ensure that one is doing so with noble intentions and not for any ulterior motives. One must also be sure not to exaggerate any such information when one relates it.
Closely related to the prohibition of revealing the secrets of others is the prohibition to read the mail or other documentation which is addressed to others. So too, one may not listen to other people’s phone conversations, and other such similar activities. Not only is reading other people’s mail forbidden, it is even forbidden to open envelopes and packages addressed to others, even if one has no intention of examining the contents. One is permitted to read documents and other materials which have been discarded or if it is clear that the person they belong to would not mind. As such, postcards and other explicitly exposed materials may be read. It is forbidden to open and read the little notes and prayers that are left at holy sites, such as at the Western Wall. Our sages teach us that the extent of the severity of revealing secrets cannot be over emphasized.
1 Devarim 27:24
2 Mishlei 11:13
3 Sanhedrin 29a
4 Sanhedrin 31a
5 Sefer Chasidim 461
6 Chafetz Chaim Issurei Rechilut 8:65, Rambam Deot 7:2
7 Yoma 4b
8 Erchin 15b
9 Hagahot Maimoniot Deot 7:7
10 Rabbeinu Yona 3:225
11 Yechave Daat 5:60, Tzitz Eliezer 15:81:2
12 Rambam Rotzeiach 1:14, C.M. 426:1
13 Rambam Sefer Hamitzvot #297
14 Sanhedrin 73a
15 Chafetz Chaim 1:4,6
16 A ruling generally attributed to Rabbeinu Gershom though some doubt exists as to its true origins. See Bnei Banim 3:17.
17 Beit David cited in Bnei Banim 3:17
18 Maharam Mirottenberg 160a, Be’er Hagola Y.D. 334
19 Bnei Banim 3:17
20 Bishvilei Haparasha p.405.
21 Orchot Chaim of the Rosh 41