diff --git a/bootstrap/src/test/java/onlydust/com/marketplace/api/it/api/feature/GoodFirstIssueCreatedNotifierJobIT.java b/bootstrap/src/test/java/onlydust/com/marketplace/api/it/api/feature/GoodFirstIssueCreatedNotifierJobIT.java
index 3553df328..e5739ab76 100644
--- a/bootstrap/src/test/java/onlydust/com/marketplace/api/it/api/feature/GoodFirstIssueCreatedNotifierJobIT.java
+++ b/bootstrap/src/test/java/onlydust/com/marketplace/api/it/api/feature/GoodFirstIssueCreatedNotifierJobIT.java
@@ -132,5 +132,11 @@ void should_notify_users_on_new_good_first_issues() throws InterruptedException
                         .withRequestBody(matchingJsonPath("$.subject", equalTo("New good first issue"))));
 
         customerIOWireMockServer.verify(2, postRequestedFor(urlEqualTo("/send/email")));
+        customerIOWireMockServer.resetAll();
+
+        // Check that notification for a single issue is sent only once
+        goodFirstIssueCreatedNotifierJob.run();
+        Thread.sleep(1000L);
+        customerIOWireMockServer.verify(0, postRequestedFor(urlEqualTo("/send/email")));
     }
 }
diff --git a/infrastructure/postgres-adapter/src/main/java/onlydust/com/marketplace/api/postgres/adapter/repository/GithubIssueViewRepository.java b/infrastructure/postgres-adapter/src/main/java/onlydust/com/marketplace/api/postgres/adapter/repository/GithubIssueViewRepository.java
index f0be7b5e4..30badd3a6 100644
--- a/infrastructure/postgres-adapter/src/main/java/onlydust/com/marketplace/api/postgres/adapter/repository/GithubIssueViewRepository.java
+++ b/infrastructure/postgres-adapter/src/main/java/onlydust/com/marketplace/api/postgres/adapter/repository/GithubIssueViewRepository.java
@@ -31,6 +31,8 @@ public interface GithubIssueViewRepository extends Repository<GithubIssueViewEnt
               and gi.status = 'OPEN'
               and gia.user_id is null
               and NOT exists(SELECT 1 FROM hackathon_issues hi WHERE hi.issue_id = gi.id)
+              and NOT exists(SELECT 1 FROM iam.notifications n WHERE n.data->'notification'->>'@type' = 'GoodFirstIssueCreated'
+                                                               AND cast(n.data->'notification'->'issue'->>'id' as bigint) = gi.id)
             """, nativeQuery = true)
     List<GithubIssueViewEntity> findAllGoodFirstIssuesCreatedSince5Minutes(ZonedDateTime now, String timezone);
 
diff --git a/infrastructure/postgres-adapter/src/main/resources/db/changelog/changelogs/00000028_add_indexes.sql b/infrastructure/postgres-adapter/src/main/resources/db/changelog/changelogs/00000028_add_indexes.sql
new file mode 100644
index 000000000..e8ad773b0
--- /dev/null
+++ b/infrastructure/postgres-adapter/src/main/resources/db/changelog/changelogs/00000028_add_indexes.sql
@@ -0,0 +1,5 @@
+create index if not exists notifications_data_notification_type_index
+    on iam.notifications ((data -> 'notification' ->> '@type'));
+
+create index if not exists notifications_data_notification_issue_id_index
+    on iam.notifications ((cast(data -> 'notification' -> 'issue' ->> 'id' as bigint)));
diff --git a/infrastructure/postgres-adapter/src/main/resources/db/changelog/db.changelog-master.yaml b/infrastructure/postgres-adapter/src/main/resources/db/changelog/db.changelog-master.yaml
index 9c14d9b9e..254d15dee 100644
--- a/infrastructure/postgres-adapter/src/main/resources/db/changelog/db.changelog-master.yaml
+++ b/infrastructure/postgres-adapter/src/main/resources/db/changelog/db.changelog-master.yaml
@@ -49,3 +49,5 @@ databaseChangeLog:
       file: db/changelog/changelogs/00000026_add_missing_indexes.sql
   - include:
       file: db/changelog/changelogs/00000027_restore_indexes.sql
+  - include:
+      file: db/changelog/changelogs/00000028_add_indexes.sql