The Source of Truth (SOT) setting in Brevo PushOwl decides which platform wins when a customer's marketing consent state differs between Shopify and Brevo. It is one of the most misunderstood settings in the data sync flow this guide walks through what it does, what it does not do, and exactly what happens in each scenario with worked examples.

The SOT setting has a very specific, narrow scope. Before anything else, get these four rules straight:

Important: If you are doing a fresh historical sync (e.g., brand-new Brevo account), the Shopify consent is what loads into Brevo regardless of the SOT setting, because there are no existing Brevo contacts to compare against. SOT only starts mattering once real-time updates begin.

In both modes, consent changes made inside Brevo (e.g., a customer clicks "unsubscribe" on a Brevo email) sync back to Shopify. The direction that differs is Shopify → Brevo.

Choose this option if Shopify is where you trust the customer's marketing consent state.

Assume no contact yet exists on Brevo.

Now assume contacts already exist on Brevo (with different consent):

Choose this option if Brevo is where you trust the customer's marketing consent state typically because you have been building your Brevo list for a while and do not want Shopify updates to overwrite it.

Under Brevo SOT, you'll see two groups of checkboxes:

Each checkbox allows consent of that channel to flow in that direction. With Brevo SOT, these are unchecked by default on the Shopify → Brevo side that's what preserves Brevo's consent.

If you check a box on the Shopify → Brevo side (e.g., "Email subscription status"), you are explicitly telling Brevo PushOwl: "for this channel, let Shopify override Brevo." This mixes the two modes and may introduce inconsistencies, so only enable the override if you know why.

Tip: There is also a top-level checkbox: "I want to keep my data consistent across Brevo and Shopify." Checking it enables full two-way consent sync (all four checkboxes on), which guarantees consistency but effectively makes Shopify behave like the source of truth for any channel whose box is checked.

Assume no contact yet exists on Brevo (behaves the same as Shopify SOT, contact is simply created):

Now assume contacts already exist on Brevo:

Independent of SOT direction, consent changes that originate inside Brevo always flow back to Shopify. Two common cases:

If a customer is blacklisted in Brevo (for example, they clicked the email unsubscribe link), that change is reflected on Shopify.

If the metafield_sync flag is enabled on your Brevo PushOwl integration, custom attributes that change in Brevo (e.g., date-of-birth, loyalty tier) will also sync back to Shopify as metafields, in addition to consent.

Note: If metafield_sync is enabled, every new contact created on Brevo will also be pushed to Shopify. This flag is off by default. Contact support to enable it.

No. During historical sync, there are typically no existing Brevo contacts to compare against (or you are building Brevo fresh), so Shopify consent loads as-is. SOT begins to matter only once real-time updates start flowing.

No. SOT governs future updates only. It does not rewrite or roll back consent that has already been synced.

Shopify SOT will bring Brevo in line with Shopify over time, because each Shopify update overwrites Brevo. If you prefer to consolidate in the opposite direction (make Shopify follow Brevo), Brevo SOT combined with checking the Brevo → Shopify consent checkboxes will gradually update Shopify from Brevo changes. Note that Brevo SOT only propagates when a consent change actually occurs on Brevo. It won't retroactively push historical Brevo state.

New contacts (those that don't exist on Brevo yet) are always created using Shopify's consent value, because there is no existing Brevo consent to preserve.

Yes. SOT applies to both email and SMS marketing subscription status. The "Marketing consent sync" checkboxes let you control email and SMS separately.

You've effectively asked for full two-way sync, any consent change on either side is pushed to the other. Functionally this is similar to Shopify SOT for the checked channels, but with the extra Brevo → Shopify overrides also on. This keeps both systems perfectly aligned but removes Brevo's "protection" from being overridden by Shopify.

No. Brevo SOT only affects the Shopify → Brevo direction. Consent changes that originate in Brevo always flow back to Shopify (regardless of SOT).

Still unsure? Contact the Brevo PushOwl support team with a summary of how you manage consent today. They can recommend the safest option and, if needed, help you plan the transition.