A stock-out is a failure of anticipation, and Odoo offers two very different ways to anticipate. Reordering rules act on the system: they generate procurement automatically. Alerts act on people: they tell somebody a decision is due. Most inventory problems come from expecting one to do the other's job.
What reordering rules actually do
A reordering rule defines a minimum and a maximum quantity for a product in a warehouse. When the forecasted quantity drops below the minimum, the scheduler creates procurement to bring stock back up to the maximum — a purchase order for bought goods, a manufacturing order for produced ones.
They are excellent when replenishment is mechanical: a stable supplier, a known lead time, a product you always restock the same way. They need no human in the loop, which is precisely their strength.
Where reordering rules fall short
- They act, they do not inform. If nobody validates the generated order, the situation looks handled while nothing has actually shipped.
- They are per product. A category quietly running down as a whole is invisible to them.
- They assume replenishment is the answer. Sometimes the right response is to stop selling a product, substitute another, or call the customer — decisions a rule cannot make.
- They require maintenance. Rules set two years ago against different demand quietly become wrong, and nothing signals that.
What an email alert adds
An alert puts a human in the loop. OpenC Low Stock Email Alert checks stock on a schedule you control and emails a summary table of everything currently under threshold to the users and groups you choose.
Three of its capabilities matter specifically here:
- Cumulative category thresholds — the summed quantity of a category and its sub-categories is compared to one figure, which catches the gradual erosion that per-product rules miss.
- Reuse of existing reordering rules — one of the five threshold modes reads the minimum quantity already defined in your rules, so both mechanisms work from the same number instead of drifting apart.
- A live rupture dashboard — list, kanban, graph and pivot views of every current shortage, so the email is a prompt rather than the only record.
How to combine them
- Set reordering rules on the products where replenishment is genuinely mechanical, and let them run.
- Enable alerts using the reordering rule threshold mode, so the same minimums drive both automation and notification. Nobody maintains two sets of numbers.
- Add cumulative category thresholds for families where the individual products matter less than the total.
- Send alerts to a group rather than to a person, so holidays do not create blind spots.
- Set the frequency to at most one email per day per item, so a lasting shortage is reported once rather than hourly.
Watch the forecasted versus on-hand distinction
Reordering rules work on forecasted quantity. Alerts let you choose per category between on-hand and forecasted.
Use forecasted when incoming receipts are reliable and you do not want an alarm for stock that is already on a truck. Use on hand when what matters is what a picker can physically take off the shelf today — retail counters and workshops usually want this one.
Also worth watching
Alerts tell you about the future. The Open Inventory Dashboard tells you about the present: late transfers, waiting receipts and stock move trends. A shortage caused by a receipt sitting unvalidated for a week is an operations problem, not a procurement one, and the dashboard is where that becomes visible.
Next steps
Read the full alert module documentation or see it on the shop.
Frequently asked questions
Do I have to choose between reordering rules and alerts?
No, and you should not. Rules automate procurement, alerts inform people. The alert module can even read the minimum quantities from your existing reordering rules so both use the same numbers.
Can I get an alert for a whole product category?
Yes. The cumulative category mode sums the quantities of a category and its sub-categories and compares that total to a single threshold.
Should alerts watch on-hand or forecasted stock?
Forecasted when incoming receipts are reliable and you do not want alarms for stock already in transit. On-hand when what matters is what can physically be picked today.
How do I avoid alert fatigue?
Set the frequency to at most one email per day per item or category, send to a group rather than an individual, and set a threshold of 0 on products you deliberately do not want monitored.
Does the alert module work with multiple companies?
Yes. Thresholds, recipients and email messages are stored per company.