Reb Eliezer: From Ohr Sameach website:
Michael from Pittsburgh wrote:
Dear Rabbi,
Does the “Cherem d’Rabbeinu Gershom” [“social excommunication”ed.] against reading someone’s mail also apply to E-Mail? At work we all share one E-Mail account, and sometimes I find it difficult to overcome my curiosity.
Dear Michael,
Rabbeinu Gershom (960-1040 C.E.), “The Light of the Exile,” was one of the earliest and greatest scholars of Ashkenazic Jewry, and led the most prestigious center of Talmudic learning of the day. In his times, there arose a need to institute a number of new measures, called “takanot.” These included the banning of polygamy and the requirement of mutual consent in divorce.
Amongst his most well known enactments is the one you mentioned – the prohibition against reading people’s mail. In those times, Jewish traders in different countries communicated in writing. Often their letters contained sensitive business information which could be very harmful if read by an outsider. As a safeguard against this, Rabbeinu Gershom legislated against reading people’s mail.
What about E-Mail? Is reading E-Mail on a computer screen included in the “Cherem of Rabbeinu Gershom”? I posed this question to Rabbi Chaim Pinchas Scheinberg, shlita, and he made no distinction between regular mail and E-Mail.
You wrote, however, that you share a joint account. Here, the question can be asked, “Is an E-Mail message in a joint account like a post card?” Concerning post cards there is a doubt whether or not Rabbeinu Gershom’s decree applies, since the sender seems unconcerned if others read it.
On the other hand, perhaps the sender trusts that no one will push the button and “open” the message – just as when you send a letter you expect that no one will open and read it.
I asked Rabbi Scheinberg about this as well. Here, too, he made no distinction between a joint account and a private account. People expect that no one read their messages, and it should not be done.
I hope this knowledge helps you overcome your curiosity. If not, let me remind you of the positive commandment of “v’ahavta l’reacha ka’mocha” – “Love your fellow person as yourself.” Our Sages explain this as follows: One must not do to somebody else what he wouldn’t want the other person to do to him. Would you like someone else to read your personal E-mail?
Sources:
Shulchan Aruch, Yoreh Deah 334:22.
Aruch HaShulchan 334:20.
Herald of Destiny, by Berel Wein, Shaar Press.
Leviticus 19:18, Shabbat 31a, Maharsha.