diff --git a/lisp/emacs-lisp/package.el b/lisp/emacs-lisp/package.el
index 02691ff7aa5..b784b0b0434 100644
--- a/lisp/emacs-lisp/package.el
+++ b/lisp/emacs-lisp/package.el
@@ -3089,6 +3090,8 @@ package--print-email-button
   "Insert a button whose action will send an email to RECIPIENT.
 NAME should have the form (FULLNAME . EMAIL) where FULLNAME is
 either a full name or nil, and EMAIL is a valid email address."
+  (when (stringp recipient)
+    (setq recipient (cons recipient "unknown@email.addr")))
   (when (car recipient)
     (insert (car recipient)))
   (when (and (car recipient) (cdr recipient))