The postal rule is a favourite exam point because it fixes the exact moment (and place) a contract forms, and because it behaves differently from the ordinary receipt rule. It sits within the wider law of offer and acceptance.
The general rule: acceptance on receipt
Ordinarily, acceptance is effective only when it is communicated to and received by the offeror (Entores v Miles Far East [1955] 2 QB 327 Persuasive (Eng); Brinkibon v Stahag Stahl [1983] 2 AC 34 Persuasive (Eng)). The postal rule is the exception to this, not the starting point.
The postal exception
Where the post is a contemplated method of acceptance, acceptance is complete on posting. The rule originates in Adams v Lindsell (1818) 1 B & Ald 681 Persuasive (Eng) — without it, no postal contract could ever be concluded (an infinite regress of confirmations). It applies even where the letter is lost and never delivered (Household Fire Insurance v Grant (1879) 4 Ex D 216 (1878–79) LR 4 Ex 216 Persuasive (Eng)).
Irish law adopts the rule. In Sanderson v Cunningham [1919] 2 IR 234 Binding (IE) an insurance contract was formed where the acceptance was posted, not where it was received. The Supreme Court applied the rule in Kelly v Cruise Catering [1994] 2 ILRM 394 Binding (IE, SC), holding that the possibility of occasional injustice is no reason not to apply it — the contract was formed in Dublin on posting the counter-signed contract. In Phoenix Rock Enterprises v Hughes [2025] IEHC 126 Binding (IE, HC), the High Court stressed that the rule is a limited exception that applies only where the parties intended agreement to be concluded that way.
When the postal rule does not apply
- Contrary wording. The rule is ousted where the offer requires actual communication — e.g. an option exercisable by notice in writing to the offeror needs receipt (Holwell Securities v Hughes [1974] 1 WLR 155 Persuasive (Eng)).
- Mis-addressed or improperly posted letters. The rule does not protect a letter wrongly addressed through the acceptor's own carelessness.
- Where it was not reasonable to use the post — for example, known postal disruption.
Instantaneous and electronic communications
The postal rule does not generally apply to electronic communications. Electronic acceptance operates on a receipt basis, in line with the treatment of instantaneous communications such as telephone and telex (Entores [1955] 2 QB 327; Brinkibon [1983] 2 AC 34 Persuasive (Eng)). In Ireland, s.21 of the Electronic Commerce Act 2000 — headed "Time and place of dispatch and receipt of electronic communications" — sets out the statutory default rules for when and where an electronic communication is taken to be sent and received. Whether a given message is an offer or an acceptance still turns on how the process is structured.
The full, exam-ready version
Formation I: offer, termination, acceptance (including the postal rule), certainty and formalities — with the full case table, worked cross-border examples and a model-answer skeleton.
see the full Contract course →Frequently asked questions
Does the postal rule apply if the acceptance letter is lost?
Yes — where the post was a contemplated method, acceptance is complete on posting even if the letter is delayed or never arrives (Household Fire Insurance v Grant; Kelly v Cruise Catering).
When does the postal rule not apply?
Where the offer requires actual receipt (Holwell Securities v Hughes), where the letter is mis-addressed through the acceptor's fault, or where it was unreasonable to use the post.
Does the postal rule apply to email?
No — the postal rule does not generally apply to electronic communications. Electronic acceptance operates on a receipt basis (in line with instantaneous communications: Entores; Brinkibon), and in Ireland s.21 of the Electronic Commerce Act 2000 governs the time and place of receipt.
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