diff --git a/mailserver.env b/mailserver.env
index 77b863ff..e0b496f9 100644
--- a/mailserver.env
+++ b/mailserver.env
@@ -240,6 +240,9 @@ SMTP_ONLY=
 # self-signed => Enables self-signed certificates
 SSL_TYPE=
 
+# Provide a comma separated list of domains to additionally export the certificate from acme.json
+SSL_SNI_DOMAINS=
+
 # These are only supported with `SSL_TYPE=manual`.
 # Provide the path to your cert and key files that you've mounted access to within the container.
 SSL_CERT_PATH=