Mailbox Rule and E-mail
The general rule of contract law is that acceptance takes place when it is communicated. The “mailbox" rule, however, states that acceptance is perfected when a letter is posted—in other words, placed in the mailbox.
Today we have modern technology that is shaping our world. Such technology may also extend the mailbox rule to encompass e-mail. Some Courts have held that the mailbox rule should be expanded to cover all technology by which commercial communication may reasonably be conducted. The focus in this context should be on “reasonably." For example, if the offeree were to attempt to accept by commercially unreasonable means, the acceptance would not be effective until it had actually been received.