Hypothetical question:
If a person A communicated an offer of billable professional services via email to person B, stating that future communication would be billed, and that otherwise B should cease further communication.
Would continued email communication by B be considered acceptance of the offer (e.g. by conduct) under UK contract law?
The elements for valid contract formation are consideration, intent, and agreement. Agreement is further broken down to offer and acceptance.
Consideration isn't an issue here. Party A's consideration is to read party B's emails. Party B's consideration is to pay for it.
Intention and acceptance are more problematic. Intention here means that the parties intended for the agreement to be legally binding. The general rule is that acceptance can be by conduct. For example, if I offer to buy something from you and, without ever saying you accept the offer, you deliver it to me, that can be deemed to be acceptance. However, there is an additional element of intention that must be satisfied for acceptance by conduct. The party who carried out the act must have intended to have accepted the offer by carrying it out (BSkyB Ltd and another v HP Enterprise Services UK Ltd [2010] EWHC 86).
Intention is assessed objectively. This means that it doesn't matter what was actually in the minds of the parties. What matters is what a reasonable outside observer would think the parties intended.
So whether continued email communication by B could be considered acceptance will depend on the circumstances. If an outside observer would perceive that a genuine commercial arrangement had been made between A and B, with both sides intending to enter into the agreement, then there is a contract. If not, then there isn't.
In the case of sending an "offer" to a spammer, it's hard to see how the spammer, in continuing their spam, would intend to accept the offer or to enter into a legally binding agreement. It's more likely that their intention was simply to continue spamming you for their own reasons. That's probably what a reasonable outside observer would think.
