diff --git a/x-pack/plugin/watcher/src/main/java/org/elasticsearch/xpack/watcher/actions/email/ExecutableEmailAction.java b/x-pack/plugin/watcher/src/main/java/org/elasticsearch/xpack/watcher/actions/email/ExecutableEmailAction.java
index 1f8e87cad1f..c9a8bfca0ad 100644
--- a/x-pack/plugin/watcher/src/main/java/org/elasticsearch/xpack/watcher/actions/email/ExecutableEmailAction.java
+++ b/x-pack/plugin/watcher/src/main/java/org/elasticsearch/xpack/watcher/actions/email/ExecutableEmailAction.java
@@ -25,9 +25,12 @@ import org.elasticsearch.xpack.watcher.support.Variables;
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.atomic.AtomicLong;
 
 public class ExecutableEmailAction extends ExecutableAction<EmailAction> {
 
+    private static final AtomicLong counter = new AtomicLong(0);
+
     private final EmailService emailService;
     private final TextTemplateEngine templateEngine;
     private final HtmlSanitizer htmlSanitizer;
@@ -67,7 +70,10 @@ public class ExecutableEmailAction extends ExecutableAction<EmailAction> {
         }
 
         Email.Builder email = action.getEmail().render(templateEngine, model, htmlSanitizer, attachments);
-        email.id(actionId + "_" + ctx.id().value());
+        // the counter ensures that a different message id is generated, even if the method is called with the same parameters
+        // this may happen if a foreach loop is used for this action
+        // same message ids will result in emails not being accepted by mail servers and thus have to be prevented at all times
+        email.id(actionId + "_" + ctx.id().value() + "_" + Long.toUnsignedString(counter.incrementAndGet()));
 
         if (ctx.simulateAction(actionId)) {
             return new EmailAction.Result.Simulated(email.build());
diff --git a/x-pack/plugin/watcher/src/test/java/org/elasticsearch/xpack/watcher/actions/email/EmailActionTests.java b/x-pack/plugin/watcher/src/test/java/org/elasticsearch/xpack/watcher/actions/email/EmailActionTests.java
index 037a70602ba..9ed94359689 100644
--- a/x-pack/plugin/watcher/src/test/java/org/elasticsearch/xpack/watcher/actions/email/EmailActionTests.java
+++ b/x-pack/plugin/watcher/src/test/java/org/elasticsearch/xpack/watcher/actions/email/EmailActionTests.java
@@ -69,6 +69,7 @@ import static org.hamcrest.Matchers.hasKey;
 import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.instanceOf;
 import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.not;
 import static org.hamcrest.Matchers.notNullValue;
 import static org.hamcrest.Matchers.nullValue;
 import static org.hamcrest.Matchers.startsWith;
@@ -170,7 +171,7 @@ public class EmailActionTests extends ESTestCase {
         assertThat(result, instanceOf(EmailAction.Result.Success.class));
         assertThat(((EmailAction.Result.Success) result).account(), equalTo(account));
         Email actualEmail = ((EmailAction.Result.Success) result).email();
-        assertThat(actualEmail.id(), is("_id_" + wid.value()));
+        assertThat(actualEmail.id(), startsWith("_id_" + wid.value() + "_"));
         assertThat(actualEmail, notNullValue());
         assertThat(actualEmail.subject(), is(subject == null ? null : subject.getTemplate()));
         assertThat(actualEmail.textBody(), is(textBody == null ? null : textBody.getTemplate()));
@@ -178,6 +179,12 @@ public class EmailActionTests extends ESTestCase {
         if (dataAttachment != null) {
             assertThat(actualEmail.attachments(), hasKey("data"));
         }
+
+        // a second execution with the same parameters may not yield the same message id
+        result = executable.execute("_id", ctx, payload);
+        String oldMessageId = actualEmail.id();
+        String newMessageId = ((EmailAction.Result.Success) result).email().id();
+        assertThat(oldMessageId, is(not(newMessageId)));
     }
 
     public void testParser() throws Exception {