diff --git a/shell.nix b/shell.nix
index 46496ba..af1976a 100644
--- a/shell.nix
+++ b/shell.nix
@@ -10,6 +10,7 @@ let
     deploy
     spinneret
     lass
+    cl-smtp
     pkgs.openssl
     pkgs.openssl.out
     pkgs.openssl.dev
diff --git a/src/main.lisp b/src/main.lisp
index 709e233..d3e7bc5 100644
--- a/src/main.lisp
+++ b/src/main.lisp
@@ -8,6 +8,7 @@
 (require "bordeaux-threads")
 (require "spinneret")
 (require "lass")
+(require "cl-smtp")
 
 (defpackage tfcserver
   (:use :cl :uiop :com.inuoe.jzon :clack :serapeum :spinneret))
diff --git a/tfcserver.asd b/tfcserver.asd
index 118be06..cade6ed 100644
--- a/tfcserver.asd
+++ b/tfcserver.asd
@@ -12,7 +12,8 @@
                "com.inuoe.jzon"
                "bordeaux-threads"
                "spinneret"
-               "lass")  ;; <== list of Quicklisp dependencies
+               "lass"
+               "cl-smtp")  ;; <== list of Quicklisp dependencies
   :components ((:module "src"
                 :components
                 ((:file "main"))))