diff --git a/mailpoet/lib/Automation/Engine/Control/SubjectTransformerHandler.php b/mailpoet/lib/Automation/Engine/Control/SubjectTransformerHandler.php
index 951eba6051..470bde3598 100644
--- a/mailpoet/lib/Automation/Engine/Control/SubjectTransformerHandler.php
+++ b/mailpoet/lib/Automation/Engine/Control/SubjectTransformerHandler.php
@@ -96,12 +96,17 @@ class SubjectTransformerHandler {
    */
   public function provideAllSubjects(Trigger $trigger, Subject ...$subjects): array {
     $allSubjectsKeys = $this->subjectKeysForTrigger($trigger);
-    $allSubjectKeyTargets = array_diff($allSubjectsKeys, array_map(
+    $allSubjectKeyTargets = array_filter(
+      array_diff($allSubjectsKeys, array_map(
       function(Subject $subject): string {
         return $subject->getKey();
       },
       $subjects
-    ));
+      )),
+    function(string $target) use ($subjects): bool {
+      return $this->canSubjectsTransformTo($target, ...$subjects);
+    }
+    );
 
     $allSubjects = [];
     foreach ($subjects as $existingSubject) {
@@ -118,9 +123,17 @@ class SubjectTransformerHandler {
         }
       }
     }
-    while (count($allSubjects) < count($allSubjectsKeys)) {
-      $allSubjects = $this->provideAllSubjects($trigger, ...array_values($allSubjects));
-    }
+
+    $allSubjectsTransformed = true;
+    do {
+      foreach ($allSubjectKeyTargets as $key) {
+        if (!isset($allSubjects[$key])) {
+          $allSubjectsTransformed = false;
+          break;
+        }
+      }
+      $allSubjects = $allSubjectsTransformed ? $allSubjects : $this->provideAllSubjects($trigger, ...array_values($allSubjects));
+    } while (!$allSubjectsTransformed);
     return array_values($allSubjects);
   }
 
@@ -164,4 +177,25 @@ class SubjectTransformerHandler {
 
     return $transformerChain;
   }
+
+  private function canSubjectsTransformTo(string $target, Subject ...$subjects): bool {
+    if (
+      in_array($target, array_map(
+      function(Subject $subject): string {
+        return $subject->getKey();
+      },
+      $subjects
+      ))
+    ) {
+      return true;
+    }
+
+    foreach ($subjects as $subject) {
+      $possibleTransformations = $this->getPossibleTransformations($subject->getKey());
+      if (in_array($target, $possibleTransformations)) {
+        return true;
+      }
+    }
+    return false;
+  }
 }