diff --git a/nixos/modules/services/mail/tlsrpt.nix b/nixos/modules/services/mail/tlsrpt.nix
index 52ed3793309d..76ba800ee6c3 100644
--- a/nixos/modules/services/mail/tlsrpt.nix
+++ b/nixos/modules/services/mail/tlsrpt.nix
@@ -244,12 +244,12 @@ in
               type = with types; nullOr str;
               default =
                 if config.services.postfix.enable && config.services.postfix.setSendmail then
-                  "/run/wrappers/bin/sendmail -i -t"
+                  "/run/wrappers/bin/sendmail -i -t -f ${cfg.reportd.settings.sender_address}"
                 else
                   null;
               defaultText = lib.literalExpression ''
                 if config.services.postfix.enable && config.services.postfix.setSendmail then
-                  "/run/wrappers/bin/sendmail -i -t"
+                  "/run/wrappers/bin/sendmail -i -t -f $${cfg.reportd.settings.sender_address}"
                 else
                   null
               '';