diff --git a/types/nodemailer/lib/mailer/index.d.ts b/types/nodemailer/lib/mailer/index.d.ts
index ece591e30e..7b227da36f 100644
--- a/types/nodemailer/lib/mailer/index.d.ts
+++ b/types/nodemailer/lib/mailer/index.d.ts
@@ -137,6 +137,7 @@ declare namespace Mail {
         dkim?: DKIM.Options;
         /** method to normalize header keys for custom caseing */
         normalizeHeaderKey?(key: string): string;
+        priority?: "high"|"normal"|"low";
     }
 
     type PluginFunction = (mail: MailMessage, callback: (err?: Error | null) => void) => void;