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Black Friday 2026: see who has started

Catch the mistake before your client does.

Send a test of any campaign to your client’s test address. We check it the moment it arrives. You’ll know if a code doesn’t match the offer or a link goes nowhere.

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Free during early access. No card needed.

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We only read, and never change anything in Klaviyo.

Our email about a test, then our portal, with a made-up agency and brands. The agency’s Home, then the test’s result as its client sees it, before and after the fixes.

In numbers

  • 16seconds

    From campaign to alert, in our one timed test

  • 10 of 10

    Planted mistakes caught

  • 6,904

    Emails read for the Market, from 685 brands. Counted .

  • 8

    Permissions in Klaviyo, all read-only

What the alert said, 16 seconds later

Our own test campaign, with mistakes we planted. The most costly first, in the alert’s own words. Point at one to find it in the email.

Black Friday early access: 20% off everything

Synapse Demo demo@synapseretention.com

To our address without a first name ·

Our test campaign, as our address without a first name received it. At the top, a “View this email in your browser” link. It greets “Hi ,” and offers the codes TAKE15 and DOUBLE10. Then a “Shop early access” button, a line opening “*|FNAME|*,” and a “See everything in early access” link. Its last line reads “This is the Flow Watch demo's test campaign. Every mistake in it is planted.”
Our own test campaign, sent from our Klaviyo account on 9 October 2026. This is the copy our address without a first name received.

Synapse Retention

Campaign sent · Alert sent

Synapse Demo: 9 problems in “Black Friday early access: 20% off everything”

  1. Proof it's from you

    This email from synapseretention.com failed the check that proves it really came from you. Gmail says mail that breaks its rules may not arrive, or may land in spam.

    What to do: Turn on a branded sending domain: it proves emails come from your web address.

  2. Subject and code disagree

    The subject line says 20% off, but the code TAKE15 gives 15% off.

    What to do: Make the subject line and the code give the same discount. Otherwise a subscriber who opens for 20% is given a code for 15%.

    Only in the copy to our address without a first name.

  3. One code, two discounts

    The code DOUBLE10 is given two different discounts in one email: 10% off and 25% off.

    What to do: Give the code one discount everywhere, and check which one it takes at checkout.

6 more problems in this alert

  1. Subject and email disagree

    The subject line says 20% off, but the email says 15% off.

    What to do: Make the subject line and the email give the same discount.

    Only in the copy to our address with a first name.

  2. Discount links without a code

    The link “Shop early access” applies the code “CODE”, not a real code.

    What to do: Put the real code in the link, where it says CODE.

  3. Links that go nowhere

    The link “View this email in your browser” goes nowhere: it points to “*|ARCHIVE|*”. It's how Mailchimp writes a fill-in field, which your platform doesn't fill in.

    What to do: Point it at your email platform's own “view in browser” link, or take it out.

  4. Links that may not open

    Some email apps may not open the link “See everything in early access”: no https:// at its start.

    What to do: Change it to https://www.synapseretention.com/early-access so every email app opens it.

  5. Text subscribers shouldn't see

    Subscribers see “*|FNAME|*” where their first name should be. It's how Mailchimp writes a fill-in field, which your platform doesn't fill in.

    What to do: Use your email platform's own first-name field, with “there” for people without a name.

  6. A greeting with no name

    The greeting reads “Hi ,” for subscribers who didn't give a first name.

    What to do: Give the name a fallback, like “there”, so it reads “Hi there,”.

    Only in the copy to our address without a first name.

See the 16 seconds, and all ten mistakes we planted

How it works

Check a campaign before it goes to the full list.

  1. Add the client’s test address

    Every brand gets one of ours. In Klaviyo, open the email’s “Preview” and type it in.

  2. Send a Klaviyo test

    Click “Send test”, as you would to check the email yourself.

  3. Get the result

    We check it the moment it arrives, and email what we found. Share it with your client by a link.

Every client on one screen.

The most urgent problem first, across all your brands. A store sees its own brand the same way.

Our portal on a computer, with the same made-up agency and brands as the phone.

  • Alerts, as each email lands

    Campaigns, your welcome, and the test emails you send us. Add our two addresses to your list. One has a first name and one doesn’t, so we see both versions of each email.

  • Inside your Klaviyo account, every night

    Which key automated emails are on. The offers in automated emails, and in scheduled campaigns every 15 minutes. Spam reports, bounces and unsubscribes. Every 2 hours we check that your store’s orders still reach Klaviyo.

  • A report on the 1st of each month

    What’s still open, what we no longer see, the offers you sent and how your market moved. As a page, and as a PDF. For an agency, it carries your name and logo.

  • The Market, and a Monday email

    What the brands we follow send each week, by category. Switch on the Monday email for the week’s biggest moves. Since 7 October 2026, we only join a list with the brand’s permission.

  • A link for your client’s Klaviyo

    Your clients connect Klaviyo with a link you send. They approve on Klaviyo’s own page, and we only read.

  • Your whole team

    Everyone in your team, at no extra cost. Each person is an owner, admin, member or viewer.

What we never do

We read what we need to check your email, and nothing more.

Change anything in your Klaviyo account
Our app can only read. It asks Klaviyo for no permission to write.
Read your customers’ names, emails or details
We see how many people are on a list, never who.
Send email from your account
Our alerts and reports come from us, to your team.
Click the links in your emails, or load the hidden picture that tells a brand an email was opened
We read where each link goes from the email itself.
Show what we read to anyone else
It stays in your workspace. It’s never in the Market.

Black Friday 2026

See who has started Black Friday, and how deep they go.

Each day we count the brands we follow: who has started, with what offer, and how early.

Open the Black Friday page
Black Friday
Cyber Monday
We count every day, to

Free during early access.

No card needed. Paid plans start later, with a month’s notice.

Get early access

Brand

For your own store

$99a month

Or $990 a year: two months free.

Agency

For an agency

$199a month

Or $1,990 a year: two months free.

5 brands included, $30 a month for each one after.

Prices are in US dollars, before VAT or sales tax. See what each plan includes

What people ask first

Which email platforms does it work with?

Any. We check the emails themselves, so it doesn’t matter what sends them. Connecting an account works with Klaviyo.

Which of our emails do you see?

Every email that reaches our two addresses: campaigns to their list, and your welcome. Reminders after a visit or an order don’t reach them. Connect Klaviyo, and we check those inside your account.

Can we check a campaign before it goes out?

Yes. Each brand gets a test address of ours. Send the campaign’s test email to it, and we check it the moment it arrives. We email what we found to your workspace’s owners and admins. An agency can share it with its client, under the agency’s name.

Do you check our welcome emails?

Yes, every one that reaches us. When your welcome changes, ask for a welcome test. We give you a fresh address to add to your list. Then we check each welcome email arrives, and on time.

Try it free.

Sign up in a minute. Free during early access. No card needed.

Get early access hello@synapseretention.com

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Issued by
Synapse Retention
Signed
Mohamed Hamed, FounderMohamed Belal, Co-founder
Based in
Budapest and London · working with US brands