diff --git a/hosts/containers/matemat/default.nix b/hosts/containers/matemat/default.nix
index 2440a1e9..d844167a 100644
--- a/hosts/containers/matemat/default.nix
+++ b/hosts/containers/matemat/default.nix
@@ -37,6 +37,7 @@
   services.ssmtp = {
     enable = true;
     root = "nek0@c3d2.de";
+    useTLS = true;
     useSTARTTLS = true;
     hostName = "mail.c3d2.de:587";
     domain = "matemat.hq.c3d2.de";