diff --git a/src/js/background/sync.js b/src/js/background/sync.js
index fc6d875..98f6af0 100644
--- a/src/js/background/sync.js
+++ b/src/js/background/sync.js
@@ -128,13 +128,12 @@ const sync = {
       await sync.checkForListenersMaybeAdd();
 
       async function updateSyncIdentities() {
-        const { syncExcludeRegExp } = await browser.storage.local.get("syncExcludeRegExp");
-        const excludeRegExp = new RegExp(syncExcludeRegExp, "i");
+        const excludeRegExp = await getExcludeRegExp();
         const identities = await browser.contextualIdentities.query({});
 
         for (const identity of identities) {
           // skip excluded identities
-          if (identity.name.match(excludeRegExp)) {
+          if (excludeRegExpMatchesIdentity(excludeRegExp, identity)) {
             continue;
           }
 
@@ -334,6 +333,7 @@ async function restore() {
  */
 async function reconcileIdentities(){
   if (SYNC_DEBUG) console.log("reconcileIdentities");
+  const excludeRegExp = await getExcludeRegExp();
 
   // first delete any from the deleted list
   const deletedIdentityList =
@@ -343,6 +343,14 @@ async function reconcileIdentities(){
     const deletedCookieStoreId = 
       await identityState.lookupCookieStoreId(deletedUUID);
     if (deletedCookieStoreId){
+      if (excludeRegExp) {
+        const deletedIdentity = await identityState.get(deletedCookieStoreId);
+        // skip excluded identities
+        if (excludeRegExpMatchesIdentity(excludeRegExp, deletedIdentity)) {
+          continue;
+        }      
+      }
+
       try{
         await browser.contextualIdentities.remove(deletedCookieStoreId);
       } catch (error) {
@@ -357,6 +365,11 @@ async function reconcileIdentities(){
     await sync.storageArea.getIdentities();
   // find any local dupes created on sync storage and delete from sync storage
   for (const localIdentity of localIdentities) {
+    // skip excluded identities
+    if (excludeRegExpMatchesIdentity(excludeRegExp, localIdentity)) {
+      continue;
+    }
+
     const syncIdentitiesOfName = syncIdentitiesRemoveDupes
       .filter(identity => identity.name === localIdentity.name);
     if (syncIdentitiesOfName.length > 1) {
@@ -370,6 +383,11 @@ async function reconcileIdentities(){
     await sync.storageArea.getIdentities();
   // now compare all containers for matching names.
   for (const syncIdentity of syncIdentities) {
+    // skip excluded identities
+    if (excludeRegExpMatchesIdentity(excludeRegExp, syncIdentity)) {
+      continue;
+    }
+
     if (syncIdentity.macAddonUUID){
       const localMatch = localIdentities.find(
         localIdentity => localIdentity.name === syncIdentity.name
@@ -585,3 +603,24 @@ async function setAssignmentWithUUID(assignedSite, urlKey) {
   }
   throw new Error (`No cookieStoreId found for: ${uuid}, ${urlKey}`);
 }
+
+// Retrieve the sync exclude regexp from local storage.
+async function getExcludeRegExp() {
+  const { syncExcludeRegExp } = await browser.storage.local.get("syncExcludeRegExp");
+  if (syncExcludeRegExp) {
+    return new RegExp(syncExcludeRegExp, "i");
+  } else {
+    return false;
+  }
+}
+
+// Matching the provided exclude regexp against the provided identity and return
+// true if they match.
+function excludeRegExpMatchesIdentity(excludeRegExp, identity) {
+  if (excludeRegExp && identity.name.match(excludeRegExp)) {
+    if (SYNC_DEBUG) console.log(`Exclude regexp matches identity '${identity.name}'`);
+    return true;
+  } else {
+    return false;
+  }
+}
diff --git a/test/features/sync.test.js b/test/features/sync.test.js
index 1e4070a..d3273a0 100644
--- a/test/features/sync.test.js
+++ b/test/features/sync.test.js
@@ -187,6 +187,50 @@ describe("Sync", function() {
       this.syncHelper.lookupIdentityBy(identities, {name: "Mozilla"});
     (mozillaContainer.icon === "pet").should.be.true;
   });
+
+  it("excludeEmptyTest", async function() {
+    await this.syncHelper.stopSyncListeners();
+    await this.syncHelper.setState({}, LOCAL_DATA, TEST_CONTAINERS, []);
+    await this.syncHelper.unsetExcludeRegexp();
+
+    await this.webExt.background.window.sync.runSync();
+
+    // We excluded nothing, so all identities should be part of the sync storage.
+    const identities = await this.syncHelper.getIdentitiesFromSyncStorage();
+    TEST_CONTAINERS.length.should.equal(identities.length);
+  });
+
+  it("excludeOutgoingTest", async function() {
+    await this.syncHelper.stopSyncListeners();
+    await this.syncHelper.setState({}, LOCAL_DATA, TEST_CONTAINERS, []);
+
+    // Our outgoing container is the last test container.
+    const outgoingContainerName = TEST_CONTAINERS.at(-1).name;
+    await this.syncHelper.setExcludeRegexp(`^${outgoingContainerName}$`);
+
+    await this.webExt.background.window.sync.runSync();
+
+    // We excluded an outgoing container, so its identity should not be part of the sync storage.
+    const identities = await this.syncHelper.getIdentitiesFromSyncStorage();
+    this.syncHelper.lookupIdentityBy(identities, {name: outgoingContainerName}).should.be.false;
+  });
+
+  it("excludeIncomingTest", async function() {
+    await this.syncHelper.stopSyncListeners();
+    await this.syncHelper.setState(SYNC_DATA, LOCAL_DATA, TEST_CONTAINERS, []);
+    
+    // Our incoming container is the first that's in the sync storage but not in the local storage
+    const incomingContainerName = Object.values(SYNC_DATA).find((sync_container) =>
+      !TEST_CONTAINERS.find((local_container) => sync_container.name === local_container.name)
+    ).name;
+    await this.syncHelper.setExcludeRegexp(`^${incomingContainerName}$`);
+
+    await this.webExt.background.window.sync.runSync();
+
+    // We excluded an incoming container, so its identity should not be part of the local storage.
+    const identities = await this.webExt.browser.contextualIdentities.query({});
+    this.syncHelper.lookupIdentityBy(identities, {name: incomingContainerName}).should.be.false;
+  });
 });
 
 class SyncTestHelper {
@@ -224,7 +268,15 @@ class SyncTestHelper {
     }
     return;
   }
+
+  async setExcludeRegexp(syncExcludeRegExp) {
+    await this.webExt.browser.storage.local.set({syncExcludeRegExp});
+  }
   
+  async unsetExcludeRegexp() {
+    await this.webExt.browser.storage.local.remove("syncExcludeRegExp");
+  }
+
   async removeAllContainers() {
     const identities = await this.webExt.browser.contextualIdentities.query({});
     for (const identity of identities) {
@@ -232,6 +284,14 @@ class SyncTestHelper {
     }
   }
 
+  async getIdentitiesFromSyncStorage() {
+    const storage = await this.webExt.browser.storage.sync.get();
+    const identities = Object.fromEntries(
+      Object.entries(storage).filter(([key]) => key.startsWith("identity@@"))
+    );
+    return Object.values(identities);
+  }
+
   lookupIdentityBy(identities, options) {
     for (const identity of identities) {
       if (options && options.name) {