diff --git a/smtpd.conf b/smtpd.conf
index 567b57b..f8e1cfd 100644
--- a/smtpd.conf
+++ b/smtpd.conf
@@ -1,3 +1,8 @@
+# Before you start modifying this file, you'll want a way to debug your changes. I had
+# a great deal of trouble with invalid recipients and authentication. If you run the
+# server in the foreground (-d) with lookup traces (-T lookup) enabled, it will save
+# you a hell of a lot of time: /usr/sbin/smtpd -d -T lookup
+
 # Load and assign certificates for your mail server. You can use the certbot certificate
 # for your web domains, so long as it contains your mail server's hostname. This hostname
 # needs to match the FQDN hostname of your server or container.