diff --git a/backend/mail.py b/backend/mail.py
index 6df13a17eaa4a2a1e2f9d65042830c6c3e901dc7..bf9ac6b982c5eba9fe0029df7cf8118d076ecad2 100644
--- a/backend/mail.py
+++ b/backend/mail.py
@@ -17,7 +17,7 @@ class MailHandler(GenericHandler):
             connection.starttls()
         cert = connection.sock.getpeercert()
         self.protocol_close(connection)
-        return tls_utils.check_cert_validity(cert)[1]
+        return tls_utils.get_cert_expiry_timestamp(cert)
 
     @abstractmethod
     def protocol_init(self, host, port):