diff --git a/README.md b/README.md
index 617eeff..7de67df 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,10 @@
 This is a small project to send encrypted form data to a recipient.
 The data is encrypted using the form recipient's PGP key.
 
+Please note that this only encrypts the email being sent from the webserver
+to the recipient. You still need to protect the data being transmitted
+between the browser and the server, for example with HTTPS.
+
 ## Requirements
 Apache/NGINX with PHP and the GnuGP PHP module. The module is installed with 
 `apt install php-gnupg` on Debian and Ubuntu systems.