diff --git a/packages/mail/src/mail.d.ts b/packages/mail/src/mail.d.ts
index 2231c4f16..0d57955c5 100644
--- a/packages/mail/src/mail.d.ts
+++ b/packages/mail/src/mail.d.ts
@@ -8,6 +8,11 @@ declare class MailService {
    */
   setApiKey(apiKey: string): void;
 
+  /**
+   * Set the default request timeout (in milliseconds).
+   */
+  setTimeout(timeout: number): void;
+
   /**
    * Set substitution wrappers
    */