1 files changed, 4 insertions, 0 deletions

diff --git a/hosts/surtr/email/default.nix b/hosts/surtr/email/default.nix
index 4fa0d440..59639bec 100644
--- a/hosts/surtr/email/default.nix
+++ b/hosts/surtr/email/default.nix
@@ -201,6 +201,10 @@ in {
         smtpd_helo_required = true;
         smtpd_helo_restrictions = "permit";
 
+        smtpd_sender_restrictions = [
+          "reject_plaintext_session"
+        ];
+
         smtpd_recipient_restrictions = [
           "reject_unauth_pipelining"
           "reject_non_fqdn_recipient"