diff --git a/java/com/google/gerrit/plugins/checks/ChecksStorageUpdate.java b/java/com/google/gerrit/plugins/checks/ChecksStorageUpdate.java
new file mode 100644
index 0000000..bdf8693
--- /dev/null
+++ b/java/com/google/gerrit/plugins/checks/ChecksStorageUpdate.java
@@ -0,0 +1,47 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.plugins.checks;
+
+import com.google.gerrit.exceptions.DuplicateKeyException;
+import java.io.IOException;
+
+/**
+ * API for updating checks in the storage backend.
+ *
+ * <p>To be implemented by check storage backends.
+ */
+public interface ChecksStorageUpdate {
+  /**
+   * Creates a new check in the storage backend.
+   *
+   * @param key the key of the check that should be created
+   * @param checkUpdate the update describing the properties of the new check
+   * @return the newly created check
+   * @throws DuplicateKeyException thrown if a check with the given key already exists
+   * @throws IOException thrown in case of an I/O error
+   */
+  public Check createCheck(CheckKey key, CheckUpdate checkUpdate)
+      throws DuplicateKeyException, IOException;
+
+  /**
+   * Updates an existing check in the storage backend.
+   *
+   * @param key the key of the check that should be updated
+   * @param checkUpdate the update describing the check properties that should be updated
+   * @return the updated check
+   * @throws IOException thrown in case of an I/O error
+   */
+  public Check updateCheck(CheckKey key, CheckUpdate checkUpdate) throws IOException;
+}
diff --git a/java/com/google/gerrit/plugins/checks/ChecksUpdate.java b/java/com/google/gerrit/plugins/checks/ChecksUpdate.java
index ba58afa..f29d079 100644
--- a/java/com/google/gerrit/plugins/checks/ChecksUpdate.java
+++ b/java/com/google/gerrit/plugins/checks/ChecksUpdate.java
@@ -14,12 +14,127 @@
 
 package com.google.gerrit.plugins.checks;
 
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.exceptions.DuplicateKeyException;
+import com.google.gerrit.plugins.checks.api.CombinedCheckState;
+import com.google.gerrit.plugins.checks.email.CombinedCheckStateUpdatedSender;
+import com.google.gerrit.reviewdb.client.PatchSet;
+import com.google.gerrit.server.IdentifiedUser;
+import com.google.gerrit.server.PatchSetUtil;
+import com.google.gerrit.server.ServerInitiated;
+import com.google.gerrit.server.UserInitiated;
+import com.google.gerrit.server.notedb.ChangeNotes;
+import com.google.inject.assistedinject.Assisted;
+import com.google.inject.assistedinject.AssistedInject;
 import java.io.IOException;
+import java.util.Optional;
 
-public interface ChecksUpdate {
-  Check createCheck(CheckKey key, CheckUpdate checkUpdate)
-      throws DuplicateKeyException, IOException;
+/**
+ * API to update checks.
+ *
+ * <p>Delegates the persistence of checks to the storage layer (see {@link ChecksStorageUpdate}).
+ *
+ * <p>This class contains additional business logic for updating checks which is independent of the
+ * used storage layer (e.g. sending email notifications).
+ */
+public class ChecksUpdate {
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
 
-  Check updateCheck(CheckKey key, CheckUpdate checkUpdate) throws IOException;
+  interface Factory {
+    ChecksUpdate create(IdentifiedUser currentUser);
+
+    ChecksUpdate createWithServerIdent();
+  }
+
+  private final CombinedCheckStateCache combinedCheckStateCache;
+  private final CombinedCheckStateUpdatedSender.Factory combinedCheckStateUpdatedSenderFactory;
+  private final ChangeNotes.Factory notesFactory;
+  private final PatchSetUtil psUtil;
+  private final Optional<IdentifiedUser> currentUser;
+  private final ChecksStorageUpdate checksStorageUpdate;
+
+  @AssistedInject
+  ChecksUpdate(
+      @UserInitiated ChecksStorageUpdate checksStorageUpdate,
+      CombinedCheckStateCache combinedCheckStateCache,
+      CombinedCheckStateUpdatedSender.Factory combinedCheckStateUpdatedSenderFactory,
+      ChangeNotes.Factory notesFactory,
+      PatchSetUtil psUtil,
+      @Assisted IdentifiedUser currentUser) {
+    this.combinedCheckStateCache = combinedCheckStateCache;
+    this.combinedCheckStateUpdatedSenderFactory = combinedCheckStateUpdatedSenderFactory;
+    this.notesFactory = notesFactory;
+    this.psUtil = psUtil;
+    this.currentUser = Optional.of(currentUser);
+    this.checksStorageUpdate = checksStorageUpdate;
+  }
+
+  @AssistedInject
+  ChecksUpdate(
+      @ServerInitiated ChecksStorageUpdate checksStorageUpdate,
+      CombinedCheckStateCache combinedCheckStateCache,
+      CombinedCheckStateUpdatedSender.Factory combinedCheckStateUpdatedSenderFactory,
+      ChangeNotes.Factory notesFactory,
+      PatchSetUtil psUtil) {
+    this.combinedCheckStateCache = combinedCheckStateCache;
+    this.combinedCheckStateUpdatedSenderFactory = combinedCheckStateUpdatedSenderFactory;
+    this.notesFactory = notesFactory;
+    this.psUtil = psUtil;
+    this.currentUser = Optional.empty();
+    this.checksStorageUpdate = checksStorageUpdate;
+  }
+
+  public Check createCheck(CheckKey key, CheckUpdate checkUpdate)
+      throws DuplicateKeyException, IOException {
+    CombinedCheckState oldCombinedCheckState =
+        combinedCheckStateCache.get(key.repository(), key.patchSet());
+
+    Check check = checksStorageUpdate.createCheck(key, checkUpdate);
+
+    CombinedCheckState newCombinedCheckState =
+        combinedCheckStateCache.get(key.repository(), key.patchSet());
+    if (oldCombinedCheckState != newCombinedCheckState) {
+      sendEmail(key, newCombinedCheckState);
+    }
+
+    return check;
+  }
+
+  public Check updateCheck(CheckKey key, CheckUpdate checkUpdate) throws IOException {
+    CombinedCheckState oldCombinedCheckState =
+        combinedCheckStateCache.get(key.repository(), key.patchSet());
+
+    Check check = checksStorageUpdate.updateCheck(key, checkUpdate);
+
+    CombinedCheckState newCombinedCheckState =
+        combinedCheckStateCache.get(key.repository(), key.patchSet());
+    if (oldCombinedCheckState != newCombinedCheckState) {
+      sendEmail(key, newCombinedCheckState);
+    }
+
+    return check;
+  }
+
+  private void sendEmail(CheckKey checkKey, CombinedCheckState combinedCheckState) {
+    try {
+      CombinedCheckStateUpdatedSender sender =
+          combinedCheckStateUpdatedSenderFactory.create(
+              checkKey.repository(), checkKey.patchSet().changeId());
+
+      if (currentUser.isPresent()) {
+        sender.setFrom(currentUser.get().getAccountId());
+      }
+
+      ChangeNotes changeNotes =
+          notesFactory.create(checkKey.repository(), checkKey.patchSet().changeId());
+      PatchSet patchSet = psUtil.get(changeNotes, checkKey.patchSet());
+      sender.setPatchSet(patchSet);
+
+      sender.setCombinedCheckState(combinedCheckState);
+      sender.send();
+    } catch (Exception e) {
+      logger.atSevere().withCause(e).log(
+          "Cannot email update for change %s", checkKey.patchSet().changeId());
+    }
+  }
 }
diff --git a/java/com/google/gerrit/plugins/checks/Module.java b/java/com/google/gerrit/plugins/checks/Module.java
index 140497b..3431ec1 100644
--- a/java/com/google/gerrit/plugins/checks/Module.java
+++ b/java/com/google/gerrit/plugins/checks/Module.java
@@ -25,8 +25,12 @@
 import com.google.gerrit.plugins.checks.api.ChangeCheckAttributeFactory.GetChangeOptions;
 import com.google.gerrit.plugins.checks.api.ChangeCheckAttributeFactory.QueryChangesOptions;
 import com.google.gerrit.plugins.checks.db.NoteDbCheckersModule;
+import com.google.gerrit.plugins.checks.email.ChecksEmailModule;
 import com.google.gerrit.plugins.checks.rules.ChecksSubmitRule;
 import com.google.gerrit.server.DynamicOptions;
+import com.google.gerrit.server.IdentifiedUser;
+import com.google.gerrit.server.ServerInitiated;
+import com.google.gerrit.server.UserInitiated;
 import com.google.gerrit.server.change.ChangeAttributeFactory;
 import com.google.gerrit.server.change.ChangeETagComputation;
 import com.google.gerrit.server.git.validators.CommitValidationListener;
@@ -35,11 +39,13 @@
 import com.google.gerrit.server.restapi.change.GetChange;
 import com.google.gerrit.server.restapi.change.QueryChanges;
 import com.google.gerrit.sshd.commands.Query;
+import com.google.inject.Provides;
 
 public class Module extends FactoryModule {
   @Override
   protected void configure() {
     factory(CheckJson.AssistedFactory.class);
+    factory(ChecksUpdate.Factory.class);
     install(new NoteDbCheckersModule());
     install(CombinedCheckStateCache.module());
 
@@ -74,5 +80,19 @@
 
     install(new ApiModule());
     install(new ChecksSubmitRule.Module());
+    install(new ChecksEmailModule());
+  }
+
+  @Provides
+  @ServerInitiated
+  ChecksUpdate provideServerInitiatedChecksUpdate(ChecksUpdate.Factory factory) {
+    return factory.createWithServerIdent();
+  }
+
+  @Provides
+  @UserInitiated
+  ChecksUpdate provideUserInitiatedChecksUpdate(
+      ChecksUpdate.Factory factory, IdentifiedUser currentUser) {
+    return factory.create(currentUser);
   }
 }
diff --git a/java/com/google/gerrit/plugins/checks/db/NoteDbCheckersModule.java b/java/com/google/gerrit/plugins/checks/db/NoteDbCheckersModule.java
index 39e8d7c..efc278b 100644
--- a/java/com/google/gerrit/plugins/checks/db/NoteDbCheckersModule.java
+++ b/java/com/google/gerrit/plugins/checks/db/NoteDbCheckersModule.java
@@ -18,7 +18,7 @@
 import com.google.gerrit.plugins.checks.Checkers;
 import com.google.gerrit.plugins.checks.CheckersUpdate;
 import com.google.gerrit.plugins.checks.Checks;
-import com.google.gerrit.plugins.checks.ChecksUpdate;
+import com.google.gerrit.plugins.checks.ChecksStorageUpdate;
 import com.google.gerrit.server.IdentifiedUser;
 import com.google.gerrit.server.ServerInitiated;
 import com.google.gerrit.server.UserInitiated;
@@ -51,13 +51,13 @@
 
   @Provides
   @ServerInitiated
-  ChecksUpdate provideServerInitiatedChecksUpdate(NoteDbChecksUpdate.Factory factory) {
+  ChecksStorageUpdate provideServerInitiatedChecksUpdate(NoteDbChecksUpdate.Factory factory) {
     return factory.createWithServerIdent();
   }
 
   @Provides
   @UserInitiated
-  ChecksUpdate provideUserInitiatedChecksUpdate(
+  ChecksStorageUpdate provideUserInitiatedChecksUpdate(
       NoteDbChecksUpdate.Factory factory, IdentifiedUser currentUser) {
     return factory.create(currentUser);
   }
diff --git a/java/com/google/gerrit/plugins/checks/db/NoteDbChecksUpdate.java b/java/com/google/gerrit/plugins/checks/db/NoteDbChecksUpdate.java
index 980a1fe..467a7bd 100644
--- a/java/com/google/gerrit/plugins/checks/db/NoteDbChecksUpdate.java
+++ b/java/com/google/gerrit/plugins/checks/db/NoteDbChecksUpdate.java
@@ -29,7 +29,7 @@
 import com.google.gerrit.plugins.checks.CheckerRef;
 import com.google.gerrit.plugins.checks.CheckerUuid;
 import com.google.gerrit.plugins.checks.Checkers;
-import com.google.gerrit.plugins.checks.ChecksUpdate;
+import com.google.gerrit.plugins.checks.ChecksStorageUpdate;
 import com.google.gerrit.plugins.checks.CombinedCheckStateCache;
 import com.google.gerrit.server.GerritPersonIdent;
 import com.google.gerrit.server.IdentifiedUser;
@@ -56,7 +56,7 @@
 import org.eclipse.jgit.notes.NoteMap;
 import org.eclipse.jgit.revwalk.RevWalk;
 
-public class NoteDbChecksUpdate implements ChecksUpdate {
+public class NoteDbChecksUpdate implements ChecksStorageUpdate {
   interface Factory {
     NoteDbChecksUpdate create(IdentifiedUser currentUser);
 
diff --git a/java/com/google/gerrit/plugins/checks/email/ChecksEmailModule.java b/java/com/google/gerrit/plugins/checks/email/ChecksEmailModule.java
new file mode 100644
index 0000000..3b4e016
--- /dev/null
+++ b/java/com/google/gerrit/plugins/checks/email/ChecksEmailModule.java
@@ -0,0 +1,32 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.plugins.checks.email;
+
+import static com.google.inject.Scopes.SINGLETON;
+
+import com.google.gerrit.extensions.config.FactoryModule;
+import com.google.gerrit.extensions.registration.DynamicSet;
+import com.google.gerrit.server.mail.send.MailSoyTemplateProvider;
+
+public class ChecksEmailModule extends FactoryModule {
+  @Override
+  protected void configure() {
+    DynamicSet.bind(binder(), MailSoyTemplateProvider.class)
+        .to(ChecksMailSoyTemplateProvider.class)
+        .in(SINGLETON);
+
+    factory(CombinedCheckStateUpdatedSender.Factory.class);
+  }
+}
diff --git a/java/com/google/gerrit/plugins/checks/email/ChecksMailSoyTemplateProvider.java b/java/com/google/gerrit/plugins/checks/email/ChecksMailSoyTemplateProvider.java
new file mode 100644
index 0000000..6bcfe08
--- /dev/null
+++ b/java/com/google/gerrit/plugins/checks/email/ChecksMailSoyTemplateProvider.java
@@ -0,0 +1,33 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.plugins.checks.email;
+
+import com.google.common.collect.ImmutableSet;
+import com.google.gerrit.server.mail.send.MailSoyTemplateProvider;
+import com.google.inject.Singleton;
+import java.util.Set;
+
+@Singleton
+public class ChecksMailSoyTemplateProvider implements MailSoyTemplateProvider {
+  @Override
+  public String getPath() {
+    return "com/google/gerrit/plugins/checks/email/";
+  }
+
+  @Override
+  public Set<String> getFileNames() {
+    return ImmutableSet.of("CombinedCheckStateUpdated.soy", "CombinedCheckStateUpdatedHtml.soy");
+  }
+}
diff --git a/java/com/google/gerrit/plugins/checks/email/CombinedCheckStateUpdatedSender.java b/java/com/google/gerrit/plugins/checks/email/CombinedCheckStateUpdatedSender.java
new file mode 100644
index 0000000..560e97b
--- /dev/null
+++ b/java/com/google/gerrit/plugins/checks/email/CombinedCheckStateUpdatedSender.java
@@ -0,0 +1,78 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.plugins.checks.email;
+
+import com.google.gerrit.exceptions.EmailException;
+import com.google.gerrit.plugins.checks.api.CombinedCheckState;
+import com.google.gerrit.reviewdb.client.Change;
+import com.google.gerrit.reviewdb.client.Project;
+import com.google.gerrit.server.account.ProjectWatches.NotifyType;
+import com.google.gerrit.server.mail.send.ChangeEmail;
+import com.google.gerrit.server.mail.send.EmailArguments;
+import com.google.gerrit.server.mail.send.ReplyToChangeSender;
+import com.google.inject.Inject;
+import com.google.inject.assistedinject.Assisted;
+
+/** Send notice about an update of the combined check state of a change. */
+public class CombinedCheckStateUpdatedSender extends ReplyToChangeSender {
+  public interface Factory extends ReplyToChangeSender.Factory<CombinedCheckStateUpdatedSender> {
+    @Override
+    CombinedCheckStateUpdatedSender create(Project.NameKey project, Change.Id changeId);
+  }
+
+  private CombinedCheckState combinedCheckState;
+
+  @Inject
+  public CombinedCheckStateUpdatedSender(
+      EmailArguments args, @Assisted Project.NameKey project, @Assisted Change.Id changeId) {
+    super(args, "combinedCheckStateUpdate", ChangeEmail.newChangeData(args, project, changeId));
+  }
+
+  @Override
+  protected void init() throws EmailException {
+    super.init();
+
+    ccAllApprovals();
+    bccStarredBy();
+    includeWatchers(NotifyType.ALL_COMMENTS);
+    removeUsersThatIgnoredTheChange();
+  }
+
+  public void setCombinedCheckState(CombinedCheckState combinedCheckState) {
+    this.combinedCheckState = combinedCheckState;
+  }
+
+  @Override
+  protected void setupSoyContext() {
+    super.setupSoyContext();
+
+    if (combinedCheckState != null) {
+      soyContext.put("combinedCheckState", combinedCheckState.name());
+    }
+  }
+
+  @Override
+  protected void formatChange() throws EmailException {
+    appendText(textTemplate("CombinedCheckStateUpdated"));
+    if (useHtml()) {
+      appendHtml(soyHtmlTemplate("CombinedCheckStateUpdatedHtml"));
+    }
+  }
+
+  @Override
+  protected boolean supportsHtml() {
+    return true;
+  }
+}
diff --git a/javatests/com/google/gerrit/plugins/checks/acceptance/api/ChangeCheckInfoIT.java b/javatests/com/google/gerrit/plugins/checks/acceptance/api/ChangeCheckInfoIT.java
index a00c2cd..7bbf3ee 100644
--- a/javatests/com/google/gerrit/plugins/checks/acceptance/api/ChangeCheckInfoIT.java
+++ b/javatests/com/google/gerrit/plugins/checks/acceptance/api/ChangeCheckInfoIT.java
@@ -186,14 +186,14 @@
     checksApiFactory.revision(psId).id(checkerUuid).update(checkInput);
 
     // Incurs reload after updating check state.
-    assertThat(cache.getStats()).since(start).hasHitCount(2);
+    assertThat(cache.getStats()).since(start).hasHitCount(4);
     assertThat(cache.getStats()).since(start).hasMissCount(0);
     assertThat(cache.getReloadCount(false) - startReloadsFalse).isEqualTo(0);
     assertThat(cache.getReloadCount(true) - startReloadsTrue).isEqualTo(1);
 
     assertThat(queryChangeCheckInfo(changeId))
         .hasValue(new ChangeCheckInfo("checks", CombinedCheckState.WARNING));
-    assertThat(cache.getStats()).since(start).hasHitCount(3);
+    assertThat(cache.getStats()).since(start).hasHitCount(5);
     assertThat(cache.getStats()).since(start).hasMissCount(0);
     assertThat(cache.getReloadCount(false) - startReloadsFalse).isEqualTo(0);
     assertThat(cache.getReloadCount(true) - startReloadsTrue).isEqualTo(1);
diff --git a/javatests/com/google/gerrit/plugins/checks/acceptance/api/ChecksEmailIT.java b/javatests/com/google/gerrit/plugins/checks/acceptance/api/ChecksEmailIT.java
new file mode 100644
index 0000000..8723614
--- /dev/null
+++ b/javatests/com/google/gerrit/plugins/checks/acceptance/api/ChecksEmailIT.java
@@ -0,0 +1,241 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.plugins.checks.acceptance.api;
+
+import static com.google.common.collect.ImmutableList.toImmutableList;
+import static com.google.common.truth.Truth.assertThat;
+import static com.google.gerrit.acceptance.testsuite.project.TestProjectUpdate.allowCapability;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableListMultimap;
+import com.google.gerrit.acceptance.TestAccount;
+import com.google.gerrit.acceptance.testsuite.group.GroupOperations;
+import com.google.gerrit.acceptance.testsuite.project.ProjectOperations;
+import com.google.gerrit.acceptance.testsuite.request.RequestScopeOperations;
+import com.google.gerrit.extensions.client.ProjectWatchInfo;
+import com.google.gerrit.extensions.common.ChangeInfo;
+import com.google.gerrit.extensions.common.PluginDefinedInfo;
+import com.google.gerrit.extensions.restapi.RestApiException;
+import com.google.gerrit.plugins.checks.CheckKey;
+import com.google.gerrit.plugins.checks.CheckerUuid;
+import com.google.gerrit.plugins.checks.acceptance.AbstractCheckersTest;
+import com.google.gerrit.plugins.checks.api.ChangeCheckInfo;
+import com.google.gerrit.plugins.checks.api.CheckInput;
+import com.google.gerrit.plugins.checks.api.CheckState;
+import com.google.gerrit.plugins.checks.api.CombinedCheckState;
+import com.google.gerrit.reviewdb.client.AccountGroup;
+import com.google.gerrit.reviewdb.client.PatchSet;
+import com.google.gerrit.testing.FakeEmailSender.Message;
+import com.google.inject.Inject;
+import java.util.List;
+import org.junit.Before;
+import org.junit.Test;
+
+public class ChecksEmailIT extends AbstractCheckersTest {
+  @Inject private RequestScopeOperations requestScopeOperations;
+  @Inject private GroupOperations groupOperations;
+  @Inject private ProjectOperations projectOperations;
+
+  private TestAccount bot;
+  private CheckerUuid checkerUuid1;
+  private CheckerUuid checkerUuid2;
+  private TestAccount owner;
+  private TestAccount reviewer;
+  private TestAccount starrer;
+  private TestAccount watcher;
+  private PatchSet.Id patchSetId;
+
+  @Before
+  public void setup() throws Exception {
+    // Create a bot account, create a bots group and add the bot as member and allow the bots group
+    // to post checks.
+    bot = accountCreator.create("bot", "bot@test.com", "Bot");
+    AccountGroup.UUID botsAccountGroupUuid =
+        groupOperations.newGroup().name("bots").addMember(bot.id()).create();
+    projectOperations
+        .project(allProjects)
+        .forUpdate()
+        .add(allowCapability("checks-administrateCheckers").group(botsAccountGroupUuid))
+        .update();
+
+    // Create two required checkers.
+    checkerUuid1 = checkerOperations.newChecker().repository(project).required().create();
+    checkerUuid2 = checkerOperations.newChecker().repository(project).required().create();
+
+    // Create a change.
+    owner = admin;
+    patchSetId = createChange().getPatchSetId();
+
+    // Add a reviewer.
+    reviewer = accountCreator.create("reviewer", "reviewer@test.com", "Reviewer");
+    gApi.changes().id(patchSetId.changeId().get()).addReviewer(reviewer.username());
+
+    // Star the change from some user.
+    starrer = accountCreator.create("starred", "starrer@test.com", "Starrer");
+    requestScopeOperations.setApiUser(starrer.id());
+    gApi.accounts().self().starChange(patchSetId.changeId().toString());
+
+    // Watch all comments of change from some user.
+    watcher = accountCreator.create("watcher", "watcher@test.com", "Watcher");
+    requestScopeOperations.setApiUser(watcher.id());
+    ProjectWatchInfo projectWatchInfo = new ProjectWatchInfo();
+    projectWatchInfo.project = project.get();
+    projectWatchInfo.filter = "*";
+    projectWatchInfo.notifyAllComments = true;
+    gApi.accounts().self().setWatchedProjects(ImmutableList.of(projectWatchInfo));
+
+    // Watch only change creations from some user --> user doesn't get notified by checks plugin.
+    TestAccount changeCreationWatcher =
+        accountCreator.create(
+            "changeCreationWatcher", "changeCreationWatcher@test.com", "Change Creation Watcher");
+    requestScopeOperations.setApiUser(changeCreationWatcher.id());
+    projectWatchInfo = new ProjectWatchInfo();
+    projectWatchInfo.project = project.get();
+    projectWatchInfo.filter = "*";
+    projectWatchInfo.notifyNewChanges = true;
+    gApi.accounts().self().setWatchedProjects(ImmutableList.of(projectWatchInfo));
+
+    // Add a reviewer that ignores the change --> user doesn't get notified by checks plugin.
+    TestAccount ignorer = accountCreator.create("ignorer", "ignorer@test.com", "Ignorer");
+    requestScopeOperations.setApiUser(admin.id());
+    gApi.changes().id(patchSetId.changeId().get()).addReviewer(ignorer.username());
+    requestScopeOperations.setApiUser(ignorer.id());
+    gApi.changes().id(patchSetId.changeId().get()).ignore(true);
+
+    // Reset request scope to admin.
+    requestScopeOperations.setApiUser(admin.id());
+  }
+
+  @Test
+  public void combinedCheckUpdatedEmailAfterCheckCreation() throws Exception {
+    assertThat(getCombinedCheckState()).isEqualTo(CombinedCheckState.IN_PROGRESS);
+
+    sender.clear();
+
+    // Post a new check that changes the combined check state to FAILED.
+    requestScopeOperations.setApiUser(bot.id());
+    CheckInput input = new CheckInput();
+    input.checkerUuid = checkerUuid1.get();
+    input.state = CheckState.FAILED;
+    checksApiFactory.revision(patchSetId).create(input).get();
+    assertThat(getCombinedCheckState()).isEqualTo(CombinedCheckState.FAILED);
+
+    // Except one email because the combined check state was updated.
+    List<Message> messages = sender.getMessages();
+    assertThat(messages).hasSize(1);
+
+    Message message = messages.get(0);
+    assertThat(message.from().getName()).isEqualTo(bot.fullName() + " (Code Review)");
+    assertThat(message.body())
+        .contains("The combined check state has been updated to " + CombinedCheckState.FAILED);
+    assertThat(message.rcpt())
+        .containsExactly(
+            owner.getEmailAddress(),
+            reviewer.getEmailAddress(),
+            starrer.getEmailAddress(),
+            watcher.getEmailAddress());
+  }
+
+  @Test
+  public void noCombinedCheckUpdatedEmailOnCheckCreationIfCombinedCheckStateIsNotChanged()
+      throws Exception {
+    // Create a check that sets the combined check state to FAILED.
+    CheckKey checkKey = CheckKey.create(project, patchSetId, checkerUuid1);
+    checkOperations.newCheck(checkKey).state(CheckState.FAILED).upsert();
+    assertThat(getCombinedCheckState()).isEqualTo(CombinedCheckState.FAILED);
+
+    sender.clear();
+
+    // Post a new check that doesn't change the combined check state..
+    requestScopeOperations.setApiUser(bot.id());
+    CheckInput input = new CheckInput();
+    input.checkerUuid = checkerUuid2.get();
+    input.state = CheckState.SCHEDULED;
+    checksApiFactory.revision(patchSetId).create(input).get();
+    assertThat(getCombinedCheckState()).isEqualTo(CombinedCheckState.FAILED);
+
+    // Except that no email was sent because the combined check state was not updated.
+    assertThat(sender.getMessages()).isEmpty();
+  }
+
+  @Test
+  public void combinedCheckUpdatedEmailAfterCheckUpdate() throws Exception {
+    // Create a check that sets the combined check state to FAILED.
+    CheckKey checkKey = CheckKey.create(project, patchSetId, checkerUuid1);
+    checkOperations.newCheck(checkKey).state(CheckState.FAILED).upsert();
+    assertThat(getCombinedCheckState()).isEqualTo(CombinedCheckState.FAILED);
+
+    sender.clear();
+
+    // Update the new check so that the combined check state is changed to IN_PROGRESS.
+    requestScopeOperations.setApiUser(bot.id());
+    CheckInput input = new CheckInput();
+    input.checkerUuid = checkerUuid1.get();
+    input.state = CheckState.RUNNING;
+    checksApiFactory.revision(patchSetId).create(input).get();
+    assertThat(getCombinedCheckState()).isEqualTo(CombinedCheckState.IN_PROGRESS);
+
+    // Except one email because the combined check state was updated.
+    List<Message> messages = sender.getMessages();
+    assertThat(messages).hasSize(1);
+
+    Message message = messages.get(0);
+    assertThat(message.from().getName()).isEqualTo(bot.fullName() + " (Code Review)");
+    assertThat(message.body())
+        .contains("The combined check state has been updated to " + CombinedCheckState.IN_PROGRESS);
+    assertThat(message.rcpt())
+        .containsExactly(
+            owner.getEmailAddress(),
+            reviewer.getEmailAddress(),
+            starrer.getEmailAddress(),
+            watcher.getEmailAddress());
+  }
+
+  @Test
+  public void noCombinedCheckUpdatedEmailOnCheckUpdateIfCombinedCheckStateIsNotChanged()
+      throws Exception {
+    // Create 2 checks that set the combined check state to FAILED.
+    CheckKey checkKey1 = CheckKey.create(project, patchSetId, checkerUuid1);
+    checkOperations.newCheck(checkKey1).state(CheckState.FAILED).upsert();
+    CheckKey checkKey2 = CheckKey.create(project, patchSetId, checkerUuid2);
+    checkOperations.newCheck(checkKey2).state(CheckState.FAILED).upsert();
+    assertThat(getCombinedCheckState()).isEqualTo(CombinedCheckState.FAILED);
+
+    sender.clear();
+
+    // Update one of the checks in a way so that doesn't change the combined check state..
+    requestScopeOperations.setApiUser(bot.id());
+    CheckInput input = new CheckInput();
+    input.checkerUuid = checkerUuid2.get();
+    input.state = CheckState.SCHEDULED;
+    checksApiFactory.revision(patchSetId).create(input).get();
+    assertThat(getCombinedCheckState()).isEqualTo(CombinedCheckState.FAILED);
+
+    // Except that no email was sent because the combined check state was not updated.
+    assertThat(sender.getMessages()).isEmpty();
+  }
+
+  private CombinedCheckState getCombinedCheckState() throws RestApiException {
+    ChangeInfo changeInfo =
+        gApi.changes()
+            .id(patchSetId.changeId().get())
+            .get(ImmutableListMultimap.of("checks--combined", "true"));
+    ImmutableList<PluginDefinedInfo> infos =
+        changeInfo.plugins.stream().filter(i -> i.name.equals("checks")).collect(toImmutableList());
+    assertThat(infos).hasSize(1);
+    assertThat(infos.get(0)).isInstanceOf(ChangeCheckInfo.class);
+    return ((ChangeCheckInfo) infos.get(0)).combinedState;
+  }
+}
diff --git a/javatests/com/google/gerrit/plugins/checks/acceptance/testsuite/CheckOperationsImplTest.java b/javatests/com/google/gerrit/plugins/checks/acceptance/testsuite/CheckOperationsImplTest.java
index 6458099..1948adb 100644
--- a/javatests/com/google/gerrit/plugins/checks/acceptance/testsuite/CheckOperationsImplTest.java
+++ b/javatests/com/google/gerrit/plugins/checks/acceptance/testsuite/CheckOperationsImplTest.java
@@ -41,7 +41,6 @@
 import java.io.IOException;
 import java.sql.Timestamp;
 import java.util.Optional;
-import org.eclipse.jgit.errors.RepositoryNotFoundException;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectReader;
 import org.eclipse.jgit.lib.Ref;
@@ -91,22 +90,27 @@
         CheckKey.create(
             Project.nameKey("non-existing"), createChange().getPatchSetId(), checkerUuid);
 
-    IllegalStateException thrown =
-        assertThrows(
-            IllegalStateException.class, () -> checkOperations.newCheck(checkKey).upsert());
-    assertThat(thrown.getCause(), instanceOf(RepositoryNotFoundException.class));
+    assertThrows(IllegalStateException.class, () -> checkOperations.newCheck(checkKey).upsert());
+  }
+
+  @Test
+  public void checkCannotBeCreatedForNonExistingChange() throws Exception {
+    CheckerUuid checkerUuid = checkerOperations.newChecker().create();
+    CheckKey checkKey = CheckKey.create(project, PatchSet.id(Change.id(1), 1), checkerUuid);
+
+    assertThrows(IllegalStateException.class, () -> checkOperations.newCheck(checkKey).upsert());
   }
 
   @Test
   public void checkCannotBeCreatedForNonExistingPatchSet() throws Exception {
+    Change.Id changeId = createChange().getChange().getId();
     CheckerUuid checkerUuid = checkerOperations.newChecker().create();
-    CheckKey checkKey = CheckKey.create(project, PatchSet.id(Change.id(1), 1), checkerUuid);
+    CheckKey checkKey = CheckKey.create(project, PatchSet.id(changeId, 99), checkerUuid);
 
     IllegalStateException thrown =
         assertThrows(
             IllegalStateException.class, () -> checkOperations.newCheck(checkKey).upsert());
-    assertThat(thrown.getCause(), instanceOf(IOException.class));
-    assertThat(thrown).hasMessageThat().contains("patchset 1,1 not found");
+    assertThat(thrown).hasMessageThat().contains("patch set not found: " + changeId.get() + ",99");
   }
 
   @Test
diff --git a/resources/com/google/gerrit/plugins/checks/email/CombinedCheckStateUpdated.soy b/resources/com/google/gerrit/plugins/checks/email/CombinedCheckStateUpdated.soy
new file mode 100644
index 0000000..83d67b1
--- /dev/null
+++ b/resources/com/google/gerrit/plugins/checks/email/CombinedCheckStateUpdated.soy
@@ -0,0 +1,41 @@
+/**
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+{namespace com.google.gerrit.server.mail.template}
+
+/**
+ * The .CombinedCheckStateUpdated template will determine the contents of the email related to a
+ * change for which the combined check state was updated.
+ */
+{template .CombinedCheckStateUpdated kind="text"}
+  {@param change: ?}
+  {@param combinedCheckState: ?}
+  {@param coverLetter: ?}
+  {@param email: ?}
+  {@param patchSet: ?}
+  The combined check state has been updated to {$combinedCheckState} for patch set
+  {$patchSet.patchSetId} of this change.
+  {if $email.changeUrl} ( {$email.changeUrl} ){/if}{\n}
+  {\n}
+  Change subject: {$change.subject}{\n}
+  ......................................................................{\n}
+  {if $coverLetter}
+    {\n}
+    {\n}
+    {$coverLetter}
+    {\n}
+  {/if}
+{/template}
diff --git a/resources/com/google/gerrit/plugins/checks/email/CombinedCheckStateUpdatedHtml.soy b/resources/com/google/gerrit/plugins/checks/email/CombinedCheckStateUpdatedHtml.soy
new file mode 100644
index 0000000..8e7e5ff
--- /dev/null
+++ b/resources/com/google/gerrit/plugins/checks/email/CombinedCheckStateUpdatedHtml.soy
@@ -0,0 +1,42 @@
+/**
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+{namespace com.google.gerrit.server.mail.template}
+
+/**
+ * The .CombinedCheckStateUpdatedHtml template will determine the contents of the email related to
+ * a change for which the combined check state was updated.
+ */
+{template .CombinedCheckStateUpdatedHtml}
+  {@param combinedCheckState: ?}
+  {@param coverLetter: ?}
+  {@param email: ?}
+  {@param patchSet: ?}
+  <p>
+    The combined check state has been updated to <strong>{$combinedCheckState}</strong> for patch
+    set {$patchSet.patchSetId} of this change.
+  </p>
+
+  {if $email.changeUrl}
+    <p>
+      {call .ViewChangeButton data="all" /}
+    </p>
+  {/if}
+
+  {if $coverLetter}
+    <div style="white-space:pre-wrap">{$coverLetter}</div>
+  {/if}
+{/template}