diff --git a/testsite/group_vars/xmpp.yml b/testsite/group_vars/xmpp.yml
index 811ea5ced77a803c2e46e2481e592bf730970aa5..e907902ff73daf20389e7c73dd4f7aa8f41e93c2 100644
--- a/testsite/group_vars/xmpp.yml
+++ b/testsite/group_vars/xmpp.yml
@@ -19,6 +19,8 @@ local_mail_aliases:
 
 smtp_relay_host: mail.example.com
 
+smtp_relay_truststore: /etc/ssl/certs/example_ca_chain.pem
+
 prosody_administrators:
   - john.doe@example.com