A customer buys a consumable product. Two months later, they may need more. Should your business automatically send a “buy again” message on day sixty? No. An estimated usage cycle is not proof of current demand, and a previous purchase is not permission for promotional messaging.
Start with permission and a reviewable assumption
For office supplies, filters or other repeat-purchase items, keep the product, purchase date and estimated replenishment interval as separate fields. Consumption varies by quantity and customer use. A forecast date is not a confirmed reorder date.
This differs from notifying someone that an out-of-stock product has returned. That customer asked about an unavailable item. A replenishment reminder follows a completed purchase, with a different expectation and consent context.
An old invoice is not a marketing subscription
During service or after the purchase, ask whether the customer wants a reminder when they might need to reorder. Explain which business will contact them, what kind of message they will receive and on which channel. Make refusal easy. Record when, where and for what category consent was given, and stop when the customer withdraws it.
The WhatsApp Business Messaging Policy, updated September 23, 2026, requires recipient opt-in and honoring opt-outs. WhatsApp's official Marketing Messages page describes re-engagement and product recommendations as marketing use cases. Do not automatically label a reorder prompt as a utility message. Check the applicable category and template requirements.
Test the timing rather than pretending to know it
Imagine a printer-supply seller. One office may use a box of cartridges in three months; another might finish it in three weeks. Instead of broadcasting to every past buyer, start with a small opted-in group and ask something useful: “Are your supplies running low, or would you prefer we stop these reminders?”
Do not promise an unapproved discount. Do not infer exact consumption from invoice dates. If the product has sensitive use or regulatory restrictions, check the appropriateness and channel rules before sending anything.
Keep an operational record you can audit
For each opted-in contact, record product and quantity, purchase date, estimated usage range and its basis, review date, consent status, last message and outcome. Pause a reminder if product availability has changed or the estimate is stale.
Review consent-valid send rate, useful replies, opt-outs and completed repeat orders each month. Compare with a similar untreated group before attributing incremental orders to the messages. Revenue is not profit: subtract product, fulfillment, messaging and operating costs when evaluating whether the program is worthwhile.
What Mr. AI can and cannot do
Mr. AI supports replies grounded in company knowledge, follow-up, summaries and human intervention across WhatsApp, Messenger and website chat. This is not a claim of a built-in purchase-history integration, automatic consumption prediction or ready-made reorder campaigns. Pilot a small manual workflow first, then try Mr. AI to assess how your team maintains context across customer conversations.
