What is the mailbox rule?

The common law mailbox rule is a frequent topic on bar and law school exams.  The rule governs when an offer is accepted.   The law only applies to communications by mail or by some type of delivery service.  Your state may have law determining whether and how the mailbox rule applies to emails and texts.  The law does not apply to face-to-face discussions or telephone calls.

An Acceptance is Effective by Mail Once it is Sent

The rule is this:  An offer is accepted once the offeree sends his acceptance by mail, provided he addresses the acceptance correctly.  That’s it.  There’s one exception where the offeree sends more than one communication and I talk about that below.  Everything else in the exam is meant to confuse you.  The mailbox rule does not apply to anything except for mail or courier service and only applies to acceptances – – not revocations, counteroffers, etc.

Mailbox Rule: Example

Let’s say Oliver sends a letter to Alan in which he offers to paint Alan’s fence (does anyone send letters like this?).  Maybe Oliver tells Alan in the letter that Alan has until January 16 to accept the offer.  Alan sends a properly addressed letter back to Oliver accepting the offer sometime before January 16 – – let’s say he sends the letter January 15.  Good.  The offer was accepted on January 15.  That is the mailbox rule.   Because the acceptance was sent by mail, the acceptance was effective once it was sent.

Even if the letter doesn’t reach Oliver, the offer was accepted on January 15.  This means that if Oliver sends a letter to Alan on January 14 revoking the offer but the letter does not arrive until January 16 – – too bad, too late.  The offer was accepted on January 15.  Oliver’s revocation would not be effective until January 16, when it was received.  The mailbox rule only applies to acceptances.  We don’t care when the revocation was sent, only when it was received.  But we do care when the acceptance was mailed.

The Exception to the Mailbox Rule

Here is one exception to the mailbox rule.  Let’s say Alan rejects the offer in writing on January 15 but then accepts the offer in writing later.   If the rejection letter reaches Oliver first, the offer was rejected.  When the acceptance arrives, it is now a counteroffer.  Alan lost his power to accept the offer.

However,  if the acceptance reaches Oliver first, the offer was accepted.

Also, keep in mind, that the offeror can dictate how the offeree may accept the offer.  For example, Oliver could avoid all this confusion by telling Alan, “The only way to accept this offer is to come to my office by January 16”  – – or – – “The only way to accept this offer is by personally handing your written acceptance to me on January 16.”   But if he doesn’t specify how the offer must be accepted, then we need to remember the mailbox rule.  Your examiner will throw a lot of dates at you to confuse you.

Below is a video on the USLawEssentials YouTube channel on the mailbox rule.