diff --git a/Classes/Aspect/DebuggingAspect.php b/Classes/Aspect/DebuggingAspect.php
index e07a4f6..bdeae35 100644
--- a/Classes/Aspect/DebuggingAspect.php
+++ b/Classes/Aspect/DebuggingAspect.php
@@ -10,6 +10,7 @@
 
 /**
  * @Flow\Aspect
+ * @Flow\Introduce("class(Neos\SwiftMailer\Message)", traitName="FormatD\Mailer\Traits\InterceptionTrait")
  */
 class DebuggingAspect {
 
@@ -18,7 +19,7 @@ class DebuggingAspect {
 	 * @var array
 	 */
 	protected $settings;
-	
+
 	/**
 	 * Intercept all emails or add bcc according to package configuration
 	 *
@@ -35,6 +36,7 @@ public function interceptEmails(\Neos\Flow\Aop\JoinPointInterface $joinPoint) {
 			$message = $joinPoint->getProxy();
 
 			if ($this->settings['interceptAll']['active']) {
+
 				$oldTo = $message->getTo();
 				$oldCc = $message->getCc();
 				$oldBcc = $message->getBcc();
@@ -48,8 +50,14 @@ public function interceptEmails(\Neos\Flow\Aop\JoinPointInterface $joinPoint) {
 					}
 				}
 
+				// stop if this aspect is executed twice (happens if QueueAdaptor is installed)
+				if ($message->isIntercepted()) {
+					return;
+				}
+
 				$interceptedRecipients = key($oldTo) . ($oldCc ? ' CC: ' . key($oldCc) : '') . ($oldBcc ? ' BCC: ' . key($oldBcc) : '');
 				$message->setSubject('[intercepted '.$interceptedRecipients.'] '.$message->getSubject());
+				$message->setIntercepted(true);
 
 				$message->setCc(array());
 				$message->setBcc(array());
diff --git a/Classes/Traits/InterceptionTrait.php b/Classes/Traits/InterceptionTrait.php
new file mode 100644
index 0000000..55a8a25
--- /dev/null
+++ b/Classes/Traits/InterceptionTrait.php
@@ -0,0 +1,36 @@
+<?php
+namespace FormatD\Mailer\Traits;
+
+/*                                                                        *
+ * This script belongs to the Flow package "FormatD.Mailer".              *
+ *                                                                        */
+
+use Neos\Flow\Annotations as Flow;
+
+
+trait InterceptionTrait {
+
+	/**
+	 * @var boolean
+	 */
+	protected $intercepted = false;
+
+	/**
+	 * @return bool
+	 */
+	public function isIntercepted(): bool
+	{
+		return $this->intercepted;
+	}
+
+	/**
+	 * @param bool $intercepted
+	 */
+	public function setIntercepted(bool $intercepted): void
+	{
+		$this->intercepted = $intercepted;
+	}
+
+}
+
+?>