My bad.. read all over this 20 times and couldn’t figure it out. Hahah sometimes the easiest mistakes are the hardest to find.
Topic summary
A Shopify Flow automation for abandoned checkouts fails at the final step with a 400 error indicating “Customer does not accept marketing for customer id.”
Root Cause:
The error occurs because the customer hasn’t opted into marketing emails. Shopify only sends marketing emails to customers who have explicitly consented.
Solutions Identified:
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For Abandoned Checkout emails: Users can modify settings in the email editor within the marketing automation workflow (click “Send marketing email” action → “View email” → edit the “To:” line) to adjust recipient requirements.
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For Abandoned Cart emails: These are treated differently from Abandoned Checkout (cart abandonment occurs before reaching checkout). Marketing consent is required and cannot be bypassed due to privacy/legal reasons.
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Template/Design Issues: One user discovered their error stemmed from the email template not being saved properly or containing errors (such as referencing inactive products). Opening the email template in edit mode, fixing any errors, and saving resolved the issue.
Key Distinction: Abandoned Cart and Abandoned Checkout are separate scenarios with different consent requirements.
It is definitely a bit confusing! Let me know if you have any issues, but hopefully you can get it working the way you need.
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Actually, almost got an instant sale for the abandoned checkout after I switched it to all customers, thanks. The abandoned cart email wouldnt be send without opting in to marketing ofcourse, I mixed them up.
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Hi
I have changed the to: line in email but it still shows an error and no email has been sent to the customer either (i checked in the customers tab). Is it possible to re run the automation to send the email or i have to do it manually.
Payment reminder is not a marketing email. There is a Send Payment Reminder action in Flow
You can’t rerun this one yet. It’s also possible this failed because the customer was not subscribed to marketing.
Are you able to see what the actual error is?
This is because of the “new” way requiring consent to sending marketing emails.
The “legacy” way didn’t use to require this.
I think Shopify is just playing it safe with this one whilst we are losing potential sales. 
For abandoned checkout specifically, nothing has changed between the new automation, and the “legacy” ones in terms of this setting, it’s just done from different places now.
In both cases you have the option of sending to all customers, or only those subscribed.
Thank you for the insight, however I’m saying what I’ve noticed.
Never had the old abandoned checkout erroring on me with this error.
So obviously something has changed.
If this is still happening, I’d really love to help get it fixed for you.
Were you able to change the setting, and you’re still seeing this?
Hey TJ, I’m still seeing this.
I had a poke in the email app, notification settings , etc but didn’t see anything that would fix it. What I ended up doing this morning is to default new customers to also be subscribers, which might be dodgy but I would have hoped is a workaround to this issue.
We have to manually send the abandonment emails at the moment which is pretty frustrating.
However, this only appeared since we’re using the new automation and for people that haven’t subscribed to the newsletter.
With the legacy way, it’d just work regardless the subscription setting.
Would you be able to provide a screenshot of the workflow, and the email setup in the Send marketing email action step?
You can also privately message me if that’s easier.
Here’s the workflow, tried to move the blocks around so that they fit in the screen… 
And this is the email setup…
Thanks for sending this.
So in the email editor (if you were to click Edit email) from your second screenshot), if you then click Edit, do you see the option to change the To: line to All customers?
Doing this tells Shopify Email to send to customers even if they’re not subscribed. This feature, as noted, is only available for Abandoned Checkout.
This is it! (hopefully)
Thank you so much for tracking this down for me 
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This option is only available for the abandoned checkout automation.
I understand that, that is what this templet started as, I may have found a fix but I am not sure yet. time will tell. I will edit if it is fixed.
Thank you so much for this reply…I’ve been looking for hours for a solution and there it was…hidden in the email “to:” field. Suggestion for your team: make these emails by default to all customers
Thanks!