Throttle outgoing emails (#2168)

Adds a delay between emails sent in a tight loop. This helps avoid
triggering Gmail abuse detections.

Also updated the recipient address for billing alerts.

core/src/main/java/google/registry/config/RegistryConfig.java

@@ -879,6 +879,17 @@ public final class RegistryConfig {
       return Optional.ofNullable(config.misc.sheetExportId);
     }
 
+    /**
+     * Returns the desired delay between outgoing emails when sending in bulk.
+     *
+     * <p>Gmail apparently has unpublished limits on peak throughput over short period.
+     */
+    @Provides
+    @Config("emailThrottleDuration")
+    public static Duration provideEmailThrottleSeconds(RegistryConfigSettings config) {
+      return Duration.standardSeconds(config.misc.emailThrottleSeconds);
+    }
+
     /**
      * Returns the email address we send various alert e-mails to.
      *

core/src/main/java/google/registry/config/RegistryConfigSettings.java

@@ -208,6 +208,7 @@ public class RegistryConfigSettings {
   public static class Misc {
     public String sheetExportId;
     public boolean isEmailSendingEnabled;
+    public int emailThrottleSeconds;
     public String alertRecipientEmailAddress;
     // TODO(b/279671974): remove below field after migration
     public String newAlertRecipientEmailAddress;

core/src/main/java/google/registry/config/files/default-config.yaml

@@ -443,6 +443,9 @@ misc:
   # Whether emails may be sent. For Prod and Sandbox this should be true.
   isEmailSendingEnabled: false
 
+  # Delay between bulk messages to avoid triggering Gmail fraud checks
+  emailThrottleSeconds: 30
+
   # Address we send alert summary emails to.
   alertRecipientEmailAddress: email@example.com
 

core/src/main/java/google/registry/reporting/billing/BillingEmailUtils.java

@@ -53,7 +53,7 @@ public class BillingEmailUtils {
       GmailClient gmailClient,
       YearMonth yearMonth,
       @Config("gSuiteOutgoingEmailAddress") InternetAddress outgoingEmailAddress,
-      @Config("alertRecipientEmailAddress") InternetAddress alertRecipientAddress,
+      @Config("newAlertRecipientEmailAddress") InternetAddress alertRecipientAddress,
       @Config("invoiceEmailRecipients") ImmutableList<InternetAddress> invoiceEmailRecipients,
       @Config("invoiceReplyToEmailAddress") Optional<InternetAddress> replyToEmailAddress,
       @Config("billingBucket") String billingBucket,

core/src/main/java/google/registry/reporting/spec11/Spec11EmailUtils.java

@@ -37,11 +37,13 @@ import google.registry.model.registrar.Registrar;
 import google.registry.model.registrar.RegistrarPoc;
 import google.registry.reporting.spec11.soy.Spec11EmailSoyInfo;
 import google.registry.util.EmailMessage;
+import google.registry.util.Sleeper;
 import java.util.List;
 import java.util.Map;
 import javax.inject.Inject;
 import javax.mail.MessagingException;
 import javax.mail.internet.InternetAddress;
+import org.joda.time.Duration;
 import org.joda.time.LocalDate;
 
 /** Provides e-mail functionality for Spec11 tasks, such as sending Spec11 reports to registrars. */
@@ -57,6 +59,8 @@ public class Spec11EmailUtils {
           .build()
           .compileToTofu();
   private final GmailClient gmailClient;
+  private final Sleeper sleeper;
+  private final Duration emailThrottleDuration;
   private final InternetAddress outgoingEmailAddress;
   private final ImmutableList<InternetAddress> spec11BccEmailAddresses;
   private final InternetAddress alertRecipientAddress;
@@ -66,12 +70,16 @@ public class Spec11EmailUtils {
   @Inject
   Spec11EmailUtils(
       GmailClient gmailClient,
+      Sleeper sleeper,
+      @Config("emailThrottleDuration") Duration emailThrottleDuration,
       @Config("newAlertRecipientEmailAddress") InternetAddress alertRecipientAddress,
       @Config("spec11OutgoingEmailAddress") InternetAddress spec11OutgoingEmailAddress,
       @Config("spec11BccEmailAddresses") ImmutableList<InternetAddress> spec11BccEmailAddresses,
       @Config("spec11WebResources") ImmutableList<String> spec11WebResources,
       @Config("registryName") String registryName) {
     this.gmailClient = gmailClient;
+    this.sleeper = sleeper;
+    this.emailThrottleDuration = emailThrottleDuration;
     this.outgoingEmailAddress = spec11OutgoingEmailAddress;
     this.spec11BccEmailAddresses = spec11BccEmailAddresses;
     this.alertRecipientAddress = alertRecipientAddress;
@@ -94,6 +102,13 @@ public class Spec11EmailUtils {
     for (RegistrarThreatMatches registrarThreatMatches : registrarThreatMatchesSet) {
       RegistrarThreatMatches filteredMatches = filterOutNonPublishedMatches(registrarThreatMatches);
       if (!filteredMatches.threatMatches().isEmpty()) {
+        if (numRegistrarsEmailed > 0) {
+          try {
+            sleeper.sleep(emailThrottleDuration);
+          } catch (InterruptedException ie) {
+            throw new RuntimeException(ie);
+          }
+        }
         try {
           // Handle exceptions individually per registrar so that one failed email doesn't prevent
           // the rest from being sent.

core/src/test/java/google/registry/reporting/spec11/Spec11EmailUtilsTest.java

@@ -26,6 +26,8 @@ import static google.registry.testing.DatabaseHelper.loadByEntity;
 import static google.registry.testing.DatabaseHelper.persistActiveHost;
 import static google.registry.testing.DatabaseHelper.persistResource;
 import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.same;
 import static org.mockito.Mockito.doThrow;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
@@ -41,11 +43,13 @@ import google.registry.persistence.transaction.JpaTestExtensions.JpaIntegrationT
 import google.registry.reporting.spec11.soy.Spec11EmailSoyInfo;
 import google.registry.testing.DatabaseHelper;
 import google.registry.util.EmailMessage;
+import google.registry.util.Sleeper;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Optional;
 import javax.mail.MessagingException;
 import javax.mail.internet.InternetAddress;
+import org.joda.time.Duration;
 import org.joda.time.LocalDate;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -101,6 +105,8 @@ class Spec11EmailUtilsTest {
       new JpaTestExtensions.Builder().buildIntegrationTestExtension();
 
   @Mock private GmailClient gmailClient;
+  @Mock private Sleeper sleeper;
+  private Duration emailThrottleDuration = Duration.millis(1);
   private Spec11EmailUtils emailUtils;
   private ArgumentCaptor<EmailMessage> contentCaptor;
   private final LocalDate date = new LocalDate(2018, 7, 15);
@@ -114,6 +120,8 @@ class Spec11EmailUtilsTest {
     emailUtils =
         new Spec11EmailUtils(
             gmailClient,
+            sleeper,
+            emailThrottleDuration,
             new InternetAddress("my-receiver@test.com"),
             new InternetAddress("abuse@test.com"),
             ImmutableList.of(
@@ -128,6 +136,19 @@ class Spec11EmailUtilsTest {
     persistDomainWithHost("c.com", host);
   }
 
+  @Test
+  void testSuccess_sleepsBetweenSending() throws Exception {
+    emailUtils.emailSpec11Reports(
+        date,
+        Spec11EmailSoyInfo.MONTHLY_SPEC_11_EMAIL,
+        "Super Cool Registry Monthly Threat Detector [2018-07-15]",
+        sampleThreatMatches());
+    // We inspect individual parameters because Message doesn't implement equals().
+    verify(gmailClient, times(3)).sendEmail(any(EmailMessage.class));
+    // Sleep once between two reports sent in a tight loop. No sleep before the final alert message.
+    verify(sleeper, times(1)).sleep(same(emailThrottleDuration));
+  }
+
   @Test
   void testSuccess_emailMonthlySpec11Reports() throws Exception {
     emailUtils.emailSpec11Reports(