There are a number of contractual issues associated with e-mail. There are for example, numerous debates over the applicability of the postal rule. When sending an e-mail, there are several potential moments of acceptance. These are:
- The first moment occurs when the e-mail departs the sender’s outbox controlled by the sender. In Internet-based e-mail transactions, the e-mail cannot be recall once it has left the sender's outbox. This is a situation analogous to the postal rule.
- The next is the instant of recept of the e-mail into the recipient’s inbox. At this point, the e-mail is accessible to the recipient.
- The next possible instant that could potentially be the moment of acceptance is when the recipient collects the e-mail from the mail server into the mail client's inbox. At this point, the recipient has received the e-mail.
- Finally, there is an argument for defining the moment of acceptance as the point when the recipient has opened or read the e-mail.
The additional inclusion of features such as e-mail recall (in products such as Microsoft Outlook), read receipts and send receipts (in most e-mail servers and client) further obfuscate the moment that could be considered the time when acceptance was made.
E-mail is the digital equivalent of a letter sent through the post. All normal functions of postal mail transpire through e-mail. This includes not only the ability to send advertisements or invitations to treat (Partridge v Crittenden ), but also equally offers and acceptances.
It must be remembered that the “question of whether the mailbox rule applies to e-mail is one that the courts have not yet answered. Its applicability seems to depend on whether e-mail is deemed to be more like instantaneous communication than like traditional mail services. Unlike real time chat e-mail, however, it is probably not instantaneous in the sense of this rule.” (Cavazos & Morin, 1994).
E-mail, maybe fast, but it is not instantaneous. Failed delivery, rerouting, damage in delivery or simply delayed all arise with E-mail. For this reason, e-mail, may be argued to most closely mirror a postal letter delivery.