To control campaign and flow overlap, review both in the same customer history. Count the marketing emails each person received, decide which message should take priority, then use campaign exclusions and flow filters to prevent the less useful send. Check the skipped messages as well as the ones that went out.
A tidy campaign calendar does not tell you how busy a customer's inbox is.
You might have three campaigns planned this week. A new subscriber could also receive a welcome email, a product follow-up and a checkout reminder. That is six marketing emails for one person, even though your calendar says three.
Those numbers are an example, not a recommended weekly limit. The point is that two perfectly reasonable plans can produce one fairly unreasonable week.
Start with the customer history
Choose a recent period and look at a small, varied sample of customers. Include a new subscriber, a recent buyer, a repeat buyer and someone who has stopped clicking. Then look across a wider group to see whether the same pattern repeats.
For each person, put campaigns and flow messages in time order. Record the message, its purpose, when it was sent and what happened next. Keep transactional receipts and service updates visible, but separate from the marketing total.
Use delivery events where available to understand what was accepted by the receiving mail system. A delivered event is not proof that an email reached the main inbox or was read. Keep bounces and skipped sends separate so you do not mistake an attempted send for an email the person received.
Now ask a simpler question than “Are we sending too much?”
Did these messages make sense together?
Two useful emails can do different jobs. Two emails repeating the same offer are much harder to defend. A checkout reminder after someone has bought is a different problem again: the message is out of date.
Write down which message wins
Do not start by excluding everyone who is in a flow. Flow membership alone does not tell you whether today's campaign is useful to that person.
Instead, decide what should happen when two messages compete. Start with the combinations you actually found in the customer histories.
| When these messages overlap | Decision to make | A rule to consider |
|---|---|---|
| A welcome offer and a general sale campaign | Does the campaign add anything new for this subscriber? | Exclude subscribers receiving the same offer through the welcome flow. |
| A checkout reminder and a completed purchase | Does the reminder still describe the customer's situation? | Recheck purchase activity before the reminder sends. |
| A product guide and another pitch for that product | Does the customer need help using what they bought? | Prioritize the guide; exclude that buyer from the repeated pitch for an appropriate period. |
| A relevant campaign and an unrelated flow email | Which is more useful now, and can the other wait? | Apply a specific priority rule rather than assuming every flow must win. |
| An order receipt and a marketing campaign | Is essential order information being confused with promotion? | Keep the service message separate from marketing pressure controls. |
These are starting points to test, not universal settings. A replenishment brand and a store selling sofas should not borrow each other's timing without thinking.
Keep each rule readable. “Recent buyers of this product do not get this repeat pitch” is easier to inspect than a long exclusion built from several half-remembered exceptions.
Use timing controls as a backstop
In Klaviyo, Smart Sending can skip an enabled message when another message in that channel was sent too recently. It is a timing control, not a decision about which offer matters most. Messages with Smart Sending off can still send within the window. Skipped messages are not automatically rescheduled. Transactional messages are treated separately. See Klaviyo's Smart Sending documentation before changing the setting.
That distinction matters. A broad campaign could go first and leave a more relevant flow message skipped. Turning the setting off everywhere solves that particular skip by allowing more sends. It does not solve the underlying choice.
Decide the message priority first. Then check whether the timing settings support it.
For the wider frequency decision, use our guide to how often ecommerce brands should send email. This overlap check adds the customer-level detail that a weekly send count misses.
Check the rule at the right point
Some facts change after someone enters a flow. A customer can place an order while waiting for the next checkout reminder.
Klaviyo checks profile filters when a person enters a flow and before actions. A failed check can skip a message; it does not necessarily remove the person from every later step. For metric-triggered flows, trigger filters are checked on entry. Message-level filters affect the individual message. These are different controls. Klaviyo explains the distinction here.
Write down what must still be true when the email is due. Then confirm the rule checks that condition at that point.
Also inspect the campaign audience. A well-filtered flow cannot stop a separate campaign from repeating its offer unless the campaign has the right exclusions too.
If several flows are involved, map the relevant triggers, waits and filters together. Our Klaviyo flow optimization guide covers the broader review.
Test one overlap before rewriting everything
Pick one repeatable problem. Perhaps new subscribers receive the same offer from a welcome flow and a campaign within a short period.
Record the current audience rules and the customer message history. Change the exclusion for that specific overlap. Keep a note of the date, who is affected and what you expect to happen.
Then check two things separately:
- Did the rule work? Look at customer histories and skip reasons. Did the intended message send? Did the repeated one stop? Did anyone miss both?
- Did the customer response change? Review unique clicks, orders, unsubscribes and complaints for the affected group. Use the same definitions and allow enough time for the buying cycle.
A lower send count alone is not success. Neither is a higher click rate if the change simply removed people who rarely click. Look at the audience size and the actual customer outcomes beside the rates.
Compare similar periods and note changes in offers, traffic and audience mix. A before-and-after improvement is a useful clue, not proof that the new rule caused it. A suitable controlled comparison gives you stronger evidence when the audience is large enough.
Give the rule an owner
Put the overlap rule beside the campaign plan and in the flow notes. Name the person who checks it when a new promotion or flow is added.
Otherwise, the next campaign can quietly undo the fix. Nobody meant to send the same offer twice. Everyone just owned a different part of the plan.
You do not need a grand rebuild to start. Open one customer's history. Count campaigns and flows together. Find one message that repeated, arrived too late or competed with a better one. Fix that rule, then check what happened.
Before adding another send, read the Emerce email frequency guide and choose a sensible starting point for each audience. Then verify it against the emails those people actually receive.
For sale-specific recipient decisions, see the Black Friday email strategy guide.