diff --git a/prisma/schema.prisma b/prisma/schema.prisma
index e918a760..674a0417 100644
--- a/prisma/schema.prisma
+++ b/prisma/schema.prisma
@@ -78,6 +78,7 @@ model MailCredentials {
   updatedAt DateTime @updatedAt
   user      User     @relation(fields: [userId], references: [id], onDelete: Cascade)
 
+  @@unique([userId, email])
   @@index([userId])
 }