diff --git a/README.md b/README.md
index 6946467..3190b24 100644
--- a/README.md
+++ b/README.md
@@ -5,3 +5,15 @@ The features are
 * Apache MPM Prefork
 * PHP 5.2.17 as apache mod
 * Zend Optimizer
+
+NOTE: To enable mailing, you need to configure ssmtp. This can be done by adding a file `ADD ssmtp.conf /etc/ssmtp/` containing a config like this
+```
+# See https://linux.die.net/man/5/ssmtp.conf
+Mailhub=<Server>
+AuthUser=<User>
+AuthPass=<Pass>
+Hostname=<Senders Host>
+FromLineOverride=YES
+UseTLS=YES
+UseSTARTTLS=YES
+```