How to set an email frequency cap
Cap how often each subscriber hears from you: set Klaviyo's Smart Sending window, switch it on in busy flows, and send most to your most engaged segments.
What this is for
A frequency cap is a limit on how many marketing emails one person can get in a given stretch of time, whatever mix of campaigns and flows is running. Without one, a subscriber who browses on Monday, abandons a cart on Tuesday and is on your Wednesday campaign list can get four emails in two days and unsubscribe from all of them.
A cap works in two layers. The first is a hard minimum gap between marketing emails, which Klaviyo calls Smart Sending. The second is how often you plan to email each group, which depends on how engaged they are. Klaviyo frames the trade-off in both directions. source, checked 28 September 2026
Time needed and what you need
Time needed: about 1 hour. Setting the window and checking each flow email takes twenty minutes; building the engagement segments and a sending plan around them takes the rest.
- Klaviyo access to account settings and to every live flow
- A list of your live flows and roughly how many emails each sends a week
- Your planned campaigns for the next month
- Unsubscribe and spam complaint rates from your last few campaigns, as a baseline
The steps
Steps 1 to 4 set the hard limit. Steps 5 to 7 decide how often you choose to send to each group underneath it.
1. Pick your minimum gap between marketing emails
Decide the shortest time you are willing to leave between two marketing emails to the same person. Klaviyo's default for email is 16 hours, which in practice means no more than one marketing email a day. Stores that send daily campaigns plus several flows often leave it there; stores that send twice a week may want a longer window. source, checked 28 September 2026
2. Set the Smart Sending window in account settings
Open your account's settings from the menu under your organisation name and find the Smart Sending section for email. Change the window there. The new value does not apply straight away: anyone already emailed keeps the window that was in place when they got that email, until it runs out. source, checked 28 September 2026
3. Leave Smart Sending on for campaigns
Every new campaign has Smart Sending switched on. Turn it off only for an email that everyone must get, such as a genuine service notice or the last hours of your biggest sale, and accept that it will land on top of whatever else they received that day. source, checked 28 September 2026
4. Check Smart Sending on every flow email
Flows are where frequency caps usually break. Flow emails do not all have Smart Sending on: some pre-built flows include it and a flow you build yourself does not. Open each flow email's settings and look for the skip recently emailed profiles option. source, checked 28 September 2026
Switch it on for high-volume flows such as browse abandonment. Consider leaving it off for the first abandoned checkout email and the welcome email, which are time-sensitive and expected. Order confirmations and other transactional emails are never skipped. source, checked 28 September 2026
- On: browse abandonment, cross-sell, replenishment, winback
- Your call: second abandoned checkout email, later welcome emails
- Usually off: first welcome email, first abandoned checkout email
5. Split your list into engagement tracks
The hard limit stops pile-ups. How often you plan to send is a separate decision, and it should differ by segment. Build segments for people who opened or clicked in the last 30, 60, 90 and 180 days, and plan to send most often to the most recent group. source, checked 28 September 2026
6. Set a planned frequency for each track
For a store that sends daily, Klaviyo's reference schedule has the 30-day engaged group on daily sends and steps down from there: three a week for people who went quiet a little longer ago, then weekly. Stores that send less often shift the whole ladder down, and the least engaged group gets a sunset flow rather than a lower frequency. source, checked 28 September 2026
- Most engaged: your full calendar
- Recently quiet: every second or third campaign
- Long quiet: weekly or less, then a sunset flow
7. Let subscribers choose less
Add a frequency choice to your preference page, such as "weekly highlights only", and save the answer to a profile property. Build a segment on that property and send those people only the campaigns you mark as highlights. Someone who picks fewer emails is a subscriber you kept, not one you lost. source, checked 28 September 2026
8. Watch the numbers that tell you the cap is wrong
Check each campaign's unsubscribe and spam complaint rates against your baseline. A steady rise means you are sending too often to someone; find which track it is and step it down. Klaviyo's reference also gives a lower limit for daily open rates across all sends. source, checked 28 September 2026
A worked example
For a supplements brand with 25,000 subscribers and five campaigns a week
Worked example (an invented brand, with invented numbers)
The brand splits its list into tracks: 7,000 people engaged in the last 30 days, 6,000 engaged in the last 31 to 90 days, 5,000 engaged in the last 91 to 180 days, and 7,000 who have not engaged in 180 days and go into a sunset flow instead (7,000 + 6,000 + 5,000 + 7,000 = 25,000).
The first track gets all five campaigns, the second gets two and the third gets one. That is 35,000 + 12,000 + 5,000 = 52,000 campaign emails a week, against 125,000 if all 25,000 got all five.
With the 16-hour Smart Sending window on its campaigns and browse abandonment flow, Klaviyo skips 1,800 flow emails in the first week to people who had just received a campaign. Unsubscribes per campaign fall from 60 to 35 over the following month.
Common mistakes
Assuming a skipped email will go out later. It will not. If someone is skipped from a campaign by Smart Sending, that campaign is simply not sent to them, so do not rely on it for anything they must receive. source, checked 28 September 2026
Running an A/B test straight after a big send. If everyone in the test group was emailed too recently, they are all skipped and Klaviyo cancels the test. source, checked 28 September 2026
Setting one frequency for the whole list. Your best customers want to hear about the restock today; someone who has not opened since spring does not. A single cadence is either too much for one group or too little for the other.
Treating the cap as a substitute for a plan. Smart Sending decides who gets skipped when emails collide; it does not decide which email mattered more. Plan campaigns so they do not collide in the first place, as in a monthly email calendar.
Doing this with Tilly
Tilly's email calendar agent lays out a month of campaigns before anything is written, and that plan costs no credits, so you can check it against the cap and the tracks above first. Campaigns Tilly writes arrive in Klaviyo as drafts waiting for approval, where your Smart Sending window still applies.
Questions people ask
Does Smart Sending stop an email and a text going out on the same day?
No. Each channel has its own window and they do not affect each other. If you also send SMS, set its window separately and plan the two channels together. source, checked 28 September 2026
How many campaigns a week should a small store send?
There is no fixed right number. Start with as many as you can make worth reading, send more only to your most engaged track, and let unsubscribe and complaint rates tell you when to stop adding. The guide on picking send days and times covers where to put them.
What is a monthly sender's engagement window?
For stores that email about once a month, Klaviyo's reference schedule uses a much longer engagement window for its main track, because people have fewer chances to open. source, checked 28 September 2026
See this on your own store
Paste your store URL. The first pass takes about a minute and needs no account. Save a card (nothing is charged) and Tilly reads the whole store and works out who buys from you.