A Thumbs-Up Can Bind You: Informal Messages and Contract Risk in 2026

Most business owners do not set out to create a contract by text. They send a quick message to confirm a price, agree a delivery date or keep a project moving. Under English law, however, a binding agreement can arise without a formal document, a signature or even the word 'contract'. The question is not whether the parties intended to create a legal relationship in the abstract, but what their communications and conduct would lead a reasonable person to conclude. This guide focuses on England and Wales; Scots law and Northern Ireland have their own rules.

Why an informal message can be a contract

A contract normally requires an offer, acceptance, consideration and an intention to create legal relations. Many commercial contracts do not need to be in writing. Where writing is required, an exchange of emails or messages can sometimes satisfy the requirement if it identifies the parties, the essential terms and the fact of agreement. A thumbs-up, a 'go ahead' or a reply saying 'agreed' may amount to acceptance if the context is clear. The risk is greatest when the parties have already discussed the main terms and a short message appears to close the deal.

The practical danger is rarely a single dramatic message. It is usually a sequence: a quotation is sent, terms are discussed, a delivery date is requested, and someone replies 'that works, please proceed'. A court or tribunal may then have to decide whether that reply was an acceptance or merely an expression of willingness to continue talking. Context, previous dealings and the authority of the person sending the message all matter.

The channels most likely to create trouble

• WhatsApp and mobile messaging: sales confirmations, price variations, delivery promises and requests to 'start work' are common sources of accidental agreement.
• Email threads: sign-offs such as 'agreed', 'we accept' or 'go ahead' can close a deal, particularly where attachments or earlier messages contain the main terms.
• Collaboration tools: messages in Teams, Slack or similar platforms may record approvals, waivers or changes to scope.
• Social media and marketplace messages: direct messages can be used to negotiate and confirm orders, even where no formal platform contract is signed.
• Voicemail and call notes: although less tidy than email, they can be evidence of what was agreed. Internal CRM notes may support or undermine the company's account.

Email footers and standard terms matter, but they are not a complete answer. Terms buried in a footer, or introduced after agreement, may not be incorporated. A battle of the forms can arise where each side sends its own terms and neither clearly wins.

What 'subject to contract' really does

A 'subject to contract' label can help to show that negotiations remain non-binding until a formal document is signed. It is most effective when it is used consistently, prominently and before any apparent agreement. It is much weaker if it appears on some emails but not others, if it is hidden in a signature block, or if it is applied after the parties have already acted as though the deal was done. A label is not a magic wand. Clear words and consistent conduct are what count.

Similarly, a statement that discussions are 'non-binding' may help in early negotiations, but it will not necessarily defeat a clear offer that has been accepted by conduct. Businesses should avoid assuming that a disclaimer will rescue an otherwise careless message.

Authority: who can bind the company?

A company acts through people. Directors usually have authority to bind the company, but employees and agents may also do so where they have actual authority or where the company has held them out as having authority. Internal limits in a staff handbook do not always bind an outsider who reasonably believes that a sales manager, account director or project lead can agree the relevant terms.

The safer approach is an authority matrix that names who may approve orders, prices, discounts, variations, waivers and settlements. It should also state who may communicate with customers and suppliers about contractual changes. Junior staff should know that a friendly 'yes' can carry legal weight. Senior staff should know that a brief message can override a carefully drafted contract.

A quarterly audit in five steps

1. Inventory the channels. List the messaging, email, collaboration and social platforms used for business, including personal devices where work messages are sent.
2. Search for risk terms. Look for 'agreed', 'go ahead', 'accept', 'proceed', 'waive', 'discount', 'variation' and 'settle' in key accounts and live projects.
3. Map authority. Check whether the people sending those messages are authorised to bind the company, and whether their limits are clear.
4. Review templates and footers. Make sure standard terms, 'subject to contract' labels and approval requirements are used consistently and at the right stage.
5. Train and record. Brief staff on the policy, keep a record of training and review high-risk threads before they become disputes.

A one-page message policy for this quarter

A workable policy does not need to be long. It should say that only named approvers may confirm orders, prices, variations, waivers or settlements in writing. Staff should use approved templates for quotations and confirmations. Negotiations should be marked 'subject to contract' until signature where that reflects the commercial intention. Emojis and casual replies should not be used to approve contractual changes. Legal threats, complaints and settlement discussions should be forwarded immediately to the responsible director or adviser. Business messages should be retained in line with the retention policy and should not be deleted when a dispute is foreseeable.

The policy should also explain that a short message can be disclosable in litigation. Employees should write as though a customer, supplier, regulator or court may one day read the thread. That single instruction can prevent many accidental agreements.

When to take advice

Advice is sensible where a message may have committed the company to a significant order, a price change, a waiver of rights or a settlement. It is also sensible where the parties have exchanged inconsistent terms, where a 'subject to contract' label has been used unevenly, or where a relationship has broken down. The earlier the review, the more options usually remain.

This article provides general information, not legal advice. Specific circumstances should be reviewed by a qualified lawyer.