diff --git a/.changeset/dark-hoops-clean.md b/.changeset/dark-hoops-clean.md
new file mode 100644
index 0000000..bb736ff
--- /dev/null
+++ b/.changeset/dark-hoops-clean.md
@@ -0,0 +1,5 @@
+---
+"@codee-sh/medusa-plugin-notification-emails": patch
+---
+
+Fix external template rendering for Slack and Email workflows by treating `external_*` IDs as registry templates instead of DB templates. Update docs to clarify template ID resolution.
diff --git a/README.md b/README.md
index 0fb0784..8d6f4e5 100755
--- a/README.md
+++ b/README.md
@@ -47,6 +47,11 @@ module.exports = defineConfig({
 
 Then continue with configuration and usage guides in `docs/`.
 
+Template IDs are resolved by prefix:
+
+- IDs starting with `system` or `external` are rendered from the in-memory registry (no DB lookup).
+- Other IDs are treated as DB templates and must exist in `mpn_builder_template`.
+
 ## Documentation
 
 - [Configuration](./docs/configuration.md)
diff --git a/docs/configuration.md b/docs/configuration.md
index b41e025..6f5eab0 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -137,6 +137,11 @@ Notes:
 - if service id is unknown, template registration is skipped
 - registered templates are available as type `external`
 
+Template ID resolution:
+
+- IDs starting with `system` or `external` are rendered from the registry and are not looked up in the database.
+- Any other ID is treated as a DB template and must exist in `mpn_builder_template`.
+
 ## Minimal complete example
 
 ```typescript
diff --git a/src/workflows/mpn-builder-services/steps/email-service.ts b/src/workflows/mpn-builder-services/steps/email-service.ts
index a8f26ed..57d3c81 100644
--- a/src/workflows/mpn-builder-services/steps/email-service.ts
+++ b/src/workflows/mpn-builder-services/steps/email-service.ts
@@ -46,12 +46,14 @@ export const emailServiceStep = createStep(
 
     const templateId = input.template_id
     const isSystemTemplateId = templateId?.startsWith(TEMPLATE_TYPES.SYSTEM_TEMPLATE)
+    const isExternalTemplateId = templateId?.startsWith(TEMPLATE_TYPES.EXTERNAL_TEMPLATE)
+    const isRegistryTemplate = isSystemTemplateId || isExternalTemplateId
 
     let blocks: any[] = []
     let template: any = {}
 
-    // If it's not a system template, get the blocks from the database
-    if (!isSystemTemplateId) {
+    // If it's not a registry template, get the blocks from the database
+    if (!isRegistryTemplate) {
       const { result: templateData } = await getTemplateWorkflow(container).run({
         input: {
           template_id: templateId,
@@ -68,7 +70,7 @@ export const emailServiceStep = createStep(
 
     const { html, text, subject } =
       await templateEmailService.render({
-        templateName: isSystemTemplateId
+        templateName: isRegistryTemplate
           ? templateId
           : "base-template",
         data: input.data,
diff --git a/src/workflows/mpn-builder-services/steps/slack-service.ts b/src/workflows/mpn-builder-services/steps/slack-service.ts
index 8ffb729..3f8d8c0 100644
--- a/src/workflows/mpn-builder-services/steps/slack-service.ts
+++ b/src/workflows/mpn-builder-services/steps/slack-service.ts
@@ -46,11 +46,13 @@ export const slackServiceStep = createStep(
 
     const templateId = input.template_id
     const isSystemTemplateId = templateId?.startsWith(TEMPLATE_TYPES.SYSTEM_TEMPLATE)
+    const isExternalTemplateId = templateId?.startsWith(TEMPLATE_TYPES.EXTERNAL_TEMPLATE)
+    const isRegistryTemplate = isSystemTemplateId || isExternalTemplateId
 
     let blocks: any[] = []
 
-    // If it's not a system template, get the blocks from the database
-    if (!isSystemTemplateId) {
+    // If it's not a registry template, get the blocks from the database
+    if (!isRegistryTemplate) {
       const { result: templateData } = await getTemplateWorkflow(container).run({
         input: {
           template_id: templateId,
@@ -68,7 +70,7 @@ export const slackServiceStep = createStep(
     // TODO CHECK WHY .config is undefined in the prepareData method when using external templates
     const { blocks: renderedBlocks } =
       await templateSlackService.render({
-        templateName: isSystemTemplateId
+        templateName: isRegistryTemplate
           ? templateId
           : "base-template",
         data: input.data,