Yom Kippur is the Jewish
Day of Atonement. It falls ten days after the
Jewish New Year,
Rosh HaShanah, on the 10th of the
Jewish month of
Tishrei. These ten days are known as the
Ten Days of Repentance or, alternatively, the
Days of Awe.
In ancient times, this was the day on which the High Priest would enter the "Holy of Holies," the room in the First Temple where the Ten Commandments were kept. (In the Second Temple, this room was empty, due to the loss of the tablets upon the Babylonian destruction of the First Temple in 586 B.C.E.) Once inside this room, the priest would appeal to God for forgiveness of the sins the population had committed against Him. Traditionally, at this time the priest would invoke the ineffable name of God. Yom Kippur is the only fast day demanded in the Torah. No water or food may pass the lips of a Jew on this day. Sex, wearing of leather, and other practices are also traditionally forbidden on Yom Kippur.
Today, Jews gather in synagogues on Yom Kippur. They pray for forgiveness of their sins against God, much as the ancient Israelites did. Contrary to common misunderstanding, this forgiveness does not apply to sins committed against another person; forgiveness for such acts must be asked for and granted in person.
After the Sabbath Day (the only day mentioned in the Ten Commandments), Yom Kippur is considered the holiest day of the Jewish year.
For an excellent elaboration upon Yom Kippur and many other matters Jewish, consult Jewish Literacy by Rabbi Joseph Telushkin.
Some thoughts regarding the "
three strikes and you're forgiven" approach to
teshuvah, or repentance, for a crime against others, in the Jewish tradition. (Note that I'm no
Talmudic sage, so if anyone else feels like weighing with a more scholarly take, please...)
I think it's important to note that there are several steps involved in securing forgiveness for a sin against another person. The guiding principle, according to the Mishnah, is that the person sinned against must be appeased. Again, I'm no expert, but my understanding is that there are four "r"s necessary to true repentance: recognition, remorse, reparation, and resolution.
Recognition that what you've done is a sin; whom you've injured by the commission and how; and when and where. Why is also helpful, but sins are seldom that simple.
Remorse regarding the sin, and the injury caused thereby. True remorse is required for true repentance. This is obviously subjective, and subject to discussion amongst Jewish scholars across the ages.
Reparations are key to repentance. Without going into specific pecuniary considerations, it can be noted that from a traditional Jewish perspective, it is not possible to compensate someone you have murdered. Following this line, no appeasement of the injured party is possible, and thus murder is a truly unforgiveable sin. Two other sins are often seen as well-nigh unreedeemable: defamation of character and defrauding the public. Due to the sheer number of people involved in such sins --directly in the latter case; indirectly, by the spread of the gossip, in the former -- it is likely impossible to make the appropriate moves to repair the damage caused.
Resolution that the sinner will not repeat the sin. There is no forgiveness for the shampoo sinner. Sin, repent, repeat is not acceptable to God or neighbor.
(Ok, I made that term up.)
Apologies would generally come under the remorse and reparation stages of repentance. Email is not usually regarded by anyone -- Jewish or no --as a particularly strong medium of apology. This is especially true Judaically if one follows the apology technique of Rambam. According to that sage, the party seeking forgiveness first should approach and apologize to the injured party alone. If this apology is rejected, the sinner must again approach the injured party, this time with three witnesses, and make his or her apologies. This witnessed apology may also be rejected, in which case the seeker of forgiveness must go away and try again later, with witness troika in tow. In case of yet another rejection, a third witnessed -- and fourth overall -- approach and apology must be made, at which point forgiveness should be granted.
Withholding forgiveness after such true and repeated attempts is traditionally seen as a sin itself.
(I think it's also important to note that Jews have (widely) varying beliefs regarding the Kingdom of God or other versions of an afterlife. These beliefs are both important and interesting, but I won't address them within the context of the traditions of Yom Kippur.)
Closing on a lighter note, I hope:
Rabbi Eliezer was supposedly fond of teaching that one should be sure to repent fully on the day before one's death.
His pupils, naturally, objected: "Nu, Rabbi, does one know one will die tomorrow?"
The canny old sage, in reply: "All the better, then, to repent fully today, just in case."