I certainly don&#x27;t condone making it artificially difficult for people to cancel, but there are several reasonable points against accepting some random e-mail as cancellation. It&#x27;s not authenticated or tamper-proof, for a start. There&#x27;s no proof of whether or when it was actually delivered. It probably requires a real person to read and act on it, which may delay things like cancelling any recurring payment process, possibly beyond the point where more money has been spent.<p>For any subscription services I run, if someone mails us asking to cancel, we normally direct them to the on-site cancellation process. This does use all our normal security and log-in procedures, and is fully automated and can be used in moments at any time.<p>However, if someone did not cancel that way (or in one of the other ways we allow for in our terms) and just blocked their payment, we would be well within our legal rights to take action to recover the money they owed us. In practice we&#x27;re only charging a small amount in these cases so we&#x27;d probably just cancel their service when payment didn&#x27;t go through, but there is no guarantee any other business would make the same decision, so your strategy is risky.