diff --git a/ghost/api-version-compatibility-service/lib/api-version-compatibility-service.js b/ghost/api-version-compatibility-service/lib/api-version-compatibility-service.js
index 7e1fafc62c..d470c2f6ab 100644
--- a/ghost/api-version-compatibility-service/lib/api-version-compatibility-service.js
+++ b/ghost/api-version-compatibility-service/lib/api-version-compatibility-service.js
@@ -1,15 +1,27 @@
 class APIVersionCompatibilityService {
-    constructor({sendEmail}) {
+    /**
+     *
+     * @param {Object} options
+     * @param {Function} options.sendEmail - email sending function
+     * @param {(acceptVersion: String) => Promise<any>} options.fetchHandled - retrives already handled compatibility notifications
+     * @param {(acceptVersion: String) => Promise<any>} options.saveHandled - persists already handled compatibility notifications
+    */
+    constructor({sendEmail, fetchHandled, saveHandled}) {
         this.sendEmail = sendEmail;
+        this.fetchHandled = fetchHandled;
+        this.saveHandled = saveHandled;
     }
 
-    handleMismatch({acceptVersion, contentVersion, userAgent}) {
-        const emailTemplate = `
-            ${userAgent} integration expected Ghost version: ${acceptVersion}
-            Current Ghost version: ${contentVersion}
-        `;
+    async handleMismatch({acceptVersion, contentVersion, userAgent}) {
+        if (!await this.fetchHandled(acceptVersion)) {
+            const emailTemplate = `
+                ${userAgent} integration expected Ghost version: ${acceptVersion}
+                Current Ghost version: ${contentVersion}
+            `;
 
-        this.sendEmail(emailTemplate);
+            await this.sendEmail(emailTemplate);
+            await this.saveHandled(acceptVersion);
+        }
     }
 }
 
diff --git a/ghost/api-version-compatibility-service/test/api-version-compatibility-service.test.js b/ghost/api-version-compatibility-service/test/api-version-compatibility-service.test.js
index b5c7e0b62c..1694f2d3d2 100644
--- a/ghost/api-version-compatibility-service/test/api-version-compatibility-service.test.js
+++ b/ghost/api-version-compatibility-service/test/api-version-compatibility-service.test.js
@@ -3,10 +3,19 @@ const sinon = require('sinon');
 const APIVersionCompatibilityService = require('../index');
 
 describe('APIVersionCompatibilityService', function () {
+    afterEach(function () {
+        sinon.reset();
+    });
+
     it('Sends an email to the instance owner when fresh accept-version header mismatch detected', async function () {
         const sendEmail = sinon.spy();
+        const fetchHandled = sinon.spy();
+        const saveHandled = sinon.spy();
+
         const compatibilityService = new APIVersionCompatibilityService({
-            sendEmail
+            sendEmail,
+            fetchHandled,
+            saveHandled
         });
 
         await compatibilityService.handleMismatch({
@@ -19,4 +28,72 @@ describe('APIVersionCompatibilityService', function () {
         assert.match(sendEmail.args[0][0], /Elaborate Fox integration expected Ghost version: v4.5/);
         assert.match(sendEmail.args[0][0], /Current Ghost version: v5.1/);
     });
+
+    it('Does NOT send an email to the instance owner when previously handled accept-version header mismatch is detected', async function () {
+        const sendEmail = sinon.spy();
+        const fetchHandled = sinon.stub()
+            .onFirstCall().resolves(null)
+            .onSecondCall().resolves({});
+
+        const saveHandled = sinon.stub().resolves({});
+
+        const compatibilityService = new APIVersionCompatibilityService({
+            sendEmail,
+            fetchHandled,
+            saveHandled
+        });
+
+        await compatibilityService.handleMismatch({
+            acceptVersion: 'v4.5',
+            contentVersion: 'v5.1',
+            userAgent: 'Elaborate Fox'
+        });
+
+        assert.equal(sendEmail.calledOnce, true);
+        assert.match(sendEmail.args[0][0], /Elaborate Fox integration expected Ghost version: v4.5/);
+        assert.match(sendEmail.args[0][0], /Current Ghost version: v5.1/);
+
+        await compatibilityService.handleMismatch({
+            acceptVersion: 'v4.5',
+            contentVersion: 'v5.1',
+            userAgent: 'Elaborate Fox'
+        });
+
+        assert.equal(sendEmail.calledTwice, false);
+    });
+
+    it('Does send multiple emails to the instance owner when previously unhandled accept-version header mismatch is detected', async function () {
+        const sendEmail = sinon.spy();
+        const fetchHandled = sinon.stub()
+            .onFirstCall().resolves(null)
+            .onSecondCall().resolves(null);
+
+        const saveHandled = sinon.stub().resolves({});
+
+        const compatibilityService = new APIVersionCompatibilityService({
+            sendEmail,
+            fetchHandled,
+            saveHandled
+        });
+
+        await compatibilityService.handleMismatch({
+            acceptVersion: 'v4.5',
+            contentVersion: 'v5.1',
+            userAgent: 'Elaborate Fox'
+        });
+
+        assert.equal(sendEmail.calledOnce, true);
+        assert.match(sendEmail.args[0][0], /Elaborate Fox integration expected Ghost version: v4.5/);
+        assert.match(sendEmail.args[0][0], /Current Ghost version: v5.1/);
+
+        await compatibilityService.handleMismatch({
+            acceptVersion: 'v4.8',
+            contentVersion: 'v5.1',
+            userAgent: 'Elaborate Fox'
+        });
+
+        assert.equal(sendEmail.calledTwice, true);
+        assert.match(sendEmail.args[1][0], /Elaborate Fox integration expected Ghost version: v4.8/);
+        assert.match(sendEmail.args[1][0], /Current Ghost version: v5.1/);
+    });
 });