The automated emails stopped on 10 July.
We found the line that did it.
On 10 July 2026 a single condition was added to 26 automated flows in one bulk edit. The condition asks for a
Shopify field that most subscribers do not have, so almost nobody has been allowed into those flows since.
Nothing is wrong with the emails, the domain, the deliverability or the audience. One line of setup is doing all of it.
Days down
62
10 July to 10 September
Flows affected
26
of 38 live flows
Revenue lost so far
£28,379
£7,571 earned vs £35,950 expected
Q4 revenue at risk
£32,651
of £65,428 flows earned last Nov–Dec
1 · What the collapse looks like
Automated flow emails sent per week. The step down lands on the week of 10 July and has not recovered in the nine weeks since.
2 · Six things that did NOT change
Before naming a cause, here is what the data rules out.
Demand
Subscribers, orders, checkouts and product views are all flat or up year on year. The people who should be triggering these flows are still arriving.
Deliverability
Campaigns went out to 671,845 people in the same window with a 0.24% bounce rate, better than last year's 0.41%. Open rate rose from 63.1% to 67.8%.
Domain and authentication
DMARC is published at p=reject with reporting, SPF and DKIM both resolve. Nothing in the DNS setup would block a flow but allow a campaign.
The emails themselves
Not one of the 188 email templates in the account was edited on 10 July. No redesign, no rewrite, no new sender address.
Blocked or skipped sends
Klaviyo logs a "Dropped Email" when it refuses to send. Drops average 10 a month, the same as always. Skipped sends since 10 July are negligible.
Consent
2,764 people granted email marketing consent in August alone, and every one we inspected is marked subscribed and unsuppressed.
Every ordinary explanation is ruled out by the account's own data. Campaign email out of the same account,
on the same domain, in the same nine weeks, is healthier than last year. Only the automated flows stopped.
3 · Demand held up while the flows went silent
August 2026 against August 2025. Grey means no meaningful change, within ten per cent either way. Every input to the flows is level or growing. Only the output fell away.
4 · The one thing that did change
We read the live setup of all 38 live flows. Twenty six of them share a timestamp and a new filter.
EDITED ON 10 JULY
26
live flows, all carrying the same new condition:
Shopify Tags does not contain "b2b"
NOT EDITED
12
live flows without that condition.
All of them are still sending normally.
The split is exact. Every flow that carries the condition collapsed. Every flow that does not carry it
is unaffected, including the transactional shipping emails, the Giftnote flows and the sunset flow. There is no
in-between case.
5 · Why one line stops the emails
The condition is not wrong in spirit. It is wrong in mechanics.
- What it was meant to do. Keep wholesale and trade customers out of the consumer flows. That is a sensible goal,
and it lines up with the B2B work done that same week: a "B2B Wholesale Sign Up" flow was created on 8 July, two days before, and the wholesale welcome flow was edited on 15 July, five days after.
- What it actually does. Klaviyo can only test "does not contain" on a profile that has the field.
A profile with no Shopify customer record has no
Shopify Tags field at all, so the test cannot pass and
the profile is never allowed into the flow.
- Who that removes. Exactly the people these flows exist for. Somebody who joins the newsletter from the pop-up
and has never ordered has no Shopify customer record, therefore no
Shopify Tags field, therefore no welcome email.
- Why the damage is uneven. Flows aimed at buyers still reach the slice of customers whose Shopify record carries
a tag. Flows aimed at non-buyers reach almost nobody. That is exactly the pattern in the table below.
The scale of it. The B2B Customers list holds 775 profiles and the TRADE list 2,284,
against a main subscriber list of 119,194. To keep a few thousand wholesale contacts out, the filter shut the door on
everyone who has never placed a Shopify order.
6 · The proof, at profile level
Thirty randomly sampled profiles. The split on one field is clean.
STILL RECEIVING WELCOME EMAILS
15 of 15
Every profile that received a welcome email since 20 July has a
Shopify Tags field. Values seen: ["newsletter"], ["Shop","Login with Shop"],
and empty []. An empty list still counts as present, so those profiles pass.
RECEIVED NOTHING
15 of 15
Every profile that joined the main list between 18 and 26 August has no
Shopify Tags field at all. All are consented, none are suppressed, and none entered the welcome flow.
One worked example: a subscriber joined the list on 24 August at 21:56, consent granted, no suppression.
Their next email of any kind was a marketing campaign on 4 September, eleven days later. No welcome email was ever queued.
7 · What it has cost, flow by flow
Recipients and attributed revenue, 10 July to 9 September, 2026 against 2025.
Same 62 days, this year against last: £30,388 of flow revenue became £7,571.
The store is about 18% bigger than it was a year ago, so the fair comparison is
£35,950, and the gap is £28,379, roughly
£3,204 a week and still running.
Two rows are not part of this story: Abandoned Cart – Evergreen was already declining before July after a
restructure in January, and the two Upstackified flows were retired last year.
8 · The second cost: the list is being burned
Losing the revenue is the visible cost. Losing the subscribers is the one that carries into Q4.
- The sunset flow retires subscribers who have stopped engaging. It was not touched on 10 July and is the one flow
sending more: 1,426 emails in August 2025 against 6,541 in August 2026.
- Over the outage window it has gone from 2,595 people to 11,928.
- The reading is straightforward: subscribers who never received a welcome series never engaged, so they age into
"unengaged" and get retired. Paid media is buying email addresses that the account is then quietly retiring.
- About 5,200 people joined the main subscriber list between 10 July and 9 September.
393 of them received a welcome email. The rest are sitting on the list with no introduction to the brand.
9 · What this means for Q4
Half of last year's peak flow revenue sits in flows that are broken right now.
FLOWS EARNED NOV+DEC 2025
£65,428
across all live flows
FROM FLOWS BROKEN TODAY
£32,651
50% of the total
CHRISTMAS VARIANTS
10 clean
none carry the filter
- The good news. All ten Christmas flow variants are in draft, were last edited in December 2025 and January 2026,
and do not carry the condition. Switched on as normal they will work.
- The catch. The Christmas variants only take over in December. Last year the evergreen welcome flow carried
October and November on its own, sending 10,745 and 14,816 emails in those two months.
If this is not fixed, October and November run with the welcome series switched off.
- No seasonal cover at all. Post-purchase, winback, back-in-stock, review requests, low stock, price drop,
birthday and nurture have no Christmas twin. They stay broken until the filter is changed.
- Do not let the fix undo itself. Whoever applies the B2B exclusion again must not apply it as written, or the
Christmas variants will break the moment they go live.
10 · The fix
In order. The first item is the whole outage.
1
Change the condition, do not just delete it
In each of the 26 flows, replace Shopify Tags does not contain "b2b" with a condition that also allows a missing field: Shopify Tags does not contain "b2b" OR Shopify Tags is not set. The cleaner alternative is to drop the property test entirely and exclude the B2B Customers and TRADE lists instead, which is what it was for.
2
Test with a profile that has no Shopify record
Create a test profile with an address that has never ordered, add it to the main list, and confirm the welcome email arrives within minutes. That is the exact case that fails today, so it is the only test that proves the fix.
3
Watch the volume come back within 48 hours
Welcome sends should return to roughly 2,700 a month and total flow sends to roughly 11,000 a week. If they do not, the change has not taken.
4
Recover the 62 days of missed subscribers
About 5,200 people joined the list during the outage and received no welcome series. They are still on the list and still consented. Send them a one-off catch-up sequence before the Q4 push rather than letting them sit until the sunset flow retires them.
5
Pause or retune the sunset flow while you catch up
It is currently retiring people who were never given a chance to engage. Hold it for a few weeks, or exclude anyone who joined after 10 July, until the catch-up has run.
6
Test every Christmas variant before it goes live
They are clean today. Send one test entry through each in October so nothing else is discovered in the middle of Black Friday.
7
Put a weekly check on flow send volume
This ran for nine weeks without anyone noticing because the flows still showed as live and the configuration still looked healthy. A weekly count of flow emails sent would have caught it on day seven.
One loose end worth a look
On 1 July 2026, nine days before the outage, the account recorded 9,599 bounces in a single day,
all on the campaign side. That is a campaign sent to a stale or unverified segment rather than anything to do with the flows,
and reputation recovered: campaign bounce rate for the whole nine week window is 0.24%, better than
last year's 0.41%. It is worth identifying which send it was so it is not repeated before Q4.
Method
Everything above comes from read-only Klaviyo API pulls made on 9 and 10 September 2026.
Nothing in the account was changed. Flow configuration was read from the live flow definitions; sends, bounces, drops,
skips, subscriptions, orders and site activity from event metrics; revenue from Klaviyo's flow and campaign values
reports using the live Shopify "Placed Order" metric. Profile-level checks sampled real profiles and their event
timelines. DNS records were checked directly. Comparison windows are matched calendar dates year on year.