diff --git a/packages/marketing-pages/src/application/services/mailer.service.interface.ts b/packages/marketing-pages/src/application/services/mailer.service.interface.ts
new file mode 100644
index 0000000..4bb730a
--- /dev/null
+++ b/packages/marketing-pages/src/application/services/mailer.service.interface.ts
@@ -0,0 +1,3 @@
+export interface IMailerService {
+  sendWelcome(userId: string, email: string): Promise<void>;
+}
diff --git a/packages/marketing-pages/src/di/symbols.ts b/packages/marketing-pages/src/di/symbols.ts
index c3aab84..caf5e14 100644
--- a/packages/marketing-pages/src/di/symbols.ts
+++ b/packages/marketing-pages/src/di/symbols.ts
@@ -1,6 +1,7 @@
 export const MARKETING_PAGES_SYMBOLS = {
   IPagesRepository: Symbol.for("marketing-pages:IPagesRepository"),
   ISiteSettingsRepository: Symbol.for("marketing-pages:ISiteSettingsRepository"),
+  IMailerService: Symbol.for("@repo/marketing-pages/IMailerService"),
   // Use cases
   IGetPageBySlugUseCase: Symbol.for("marketing-pages:IGetPageBySlugUseCase"),
   IGetSiteSettingsUseCase: Symbol.for("marketing-pages:IGetSiteSettingsUseCase"),