diff --git a/diagrams/class-diagrams/runner.md b/diagrams/class-diagrams/runner.md
index 97d21e042..99e4f5d3f 100644
--- a/diagrams/class-diagrams/runner.md
+++ b/diagrams/class-diagrams/runner.md
@@ -7,14 +7,22 @@ title: GOV.UK Forms Runner app class diagram
 
 ```mermaid
 classDiagram
-	direction RL
-	class `Submission`
-	`Submission` : +jsonb answers
-	`Submission` : +jsonb form_document
-	`Submission` : +integer form_id
-	`Submission` : +string mail_message_id
-	`Submission` : +string mail_status
-	`Submission` : +string mode
-	`Submission` : +string reference
-	`Submission` : +datetime sent_at
+    direction RL
+    class `Delivery`
+    `Delivery` : +datetime delivered_at
+    `Delivery` : +string delivery_reference
+    `Delivery` : +datetime failed_at
+    `Delivery` : +string failure_reason
+    `Delivery` : +datetime last_attempt_at
+    class `Submission`
+    `Submission` : +jsonb answers
+    `Submission` : +jsonb form_document
+    `Submission` : +integer form_id
+    `Submission` : +string mode
+    `Submission` : +string reference
+    `Submission` : +string submission_locale
+    class `SubmissionDelivery`
+    `Submission` --> `SubmissionDelivery`
+    `Delivery` --> `SubmissionDelivery`
+    `Submission` "0..*" -- "0..*" `Delivery`
   ```
diff --git a/diagrams/sequence-diagrams/sending-submission-emails.md b/diagrams/sequence-diagrams/sending-submission-emails.md
index 2af74485d..95d9684f3 100644
--- a/diagrams/sequence-diagrams/sending-submission-emails.md
+++ b/diagrams/sequence-diagrams/sending-submission-emails.md
@@ -75,8 +75,7 @@ break error
 end
 
 ses->>worker: return message_id
-worker->>runner-db: set mail_message_id on Submission
-worker->>runner-db: set the last_delivery_attempt timestamp on Submission
+worker->>runner-db: create a Delivery record with the<br/> message_id from SES as the delivery_reference
 
 ses-)inbox: send email
 note over ses,inbox: happens some time later
@@ -116,15 +115,15 @@ worker->>solidqueue-db: enqueue recurring receive bounces job
 worker->>solidqueue-db: dequeue receive bounces job
 worker->>sqs: get messages from bounces and complaints queue
 alt there is a bounce SQS message
-  worker->>runner-db: get Submission by the message_id in the SQS message
-  worker->>runner-db: update delivery_status of Submission to "bounced"
+  worker->>runner-db: get Delivery where the delivery_reference is the<br/> message_id from the SQS message
+  worker->>runner-db: set the failed_at timestamp on the Delivery
   worker->>worker: Log with the submission details
   worker->>sentry: send error event
   sentry->>support: Alert via Slack
   support->>support: Identify why the email bounced
   support->>support: Run rake task to retry submission
 else there is a complaint SQS message
-  worker->>runner-db: get Submission by the message_id in the SQS message
+  worker->>runner-db: get Delivery where the delivery_reference is the<br/> message_id from the SQS message
   worker->>worker: Log with the submission details
 end
 
@@ -152,7 +151,8 @@ actor support as Forms team tech support
 worker->>solidqueue-db: enqueue recurring receive deliveries job
 worker->>solidqueue-db: dequeue receive deliveries job
 worker->>sqs: get messages from deliveries queue
-worker->>runner-db: get Submission by the message_id in the SQS message
+worker->>runner-db: get Delivery where the delivery_reference is the<br/> message_id from the SQS message
+worker->>runner-db: set the delivered_at timestamp on the Delivery
 worker->>worker: log a "form_submission_delivered" event
 note over worker,runner-db: we don't currently use the "delivered" status for anything other than for information
 ```