diff --git a/invoice-ninja.nix b/invoice-ninja.nix
index bfa19c7..38c8706 100644
--- a/invoice-ninja.nix
+++ b/invoice-ninja.nix
@@ -33,6 +33,18 @@ let
     fi
     $sudo ${phpPackage}/bin/php artisan "$@"
   '';
+
+  invoice-ninja-msmtp = pkgs.writeShellScriptBin "msmtp" ''
+    sudo=exec
+    if [[ "$USER" != ${user} ]]; then
+      sudo='exec /run/wrappers/bin/sudo -u ${user}'
+    fi
+    $sudo ${pkgs.msmtp}/bin/msmtp --auth on \
+      --tls=${if cfg.msmtp.tls then "on" else "off"} --tls-starttls=off \
+      --host=${cfg.msmtp.host} --port=${toString cfg.msmtp.port} \
+      --user=${cfg.msmtp.username} --passwordeval="${cfg.msmtp.passwordeval}" \
+      --from=${cfg.msmtp.from} "$1"
+  '';
 in
 {
   options.services.invoice-ninja = {
@@ -70,6 +82,13 @@ in
       '';
     };
 
+    mailMailer = lib.mkOption {
+      type = lib.types.enum [ "sendmail" "smtp" ];
+      default = "sendmail";
+      example = "smtp";
+      description = "Controls the method used by Invoice Ninja to send mail.";
+    };
+
     dataDir = lib.mkOption {
       type = lib.types.str;
       default = "/var/lib/invoice-ninja";
@@ -165,6 +184,43 @@ in
       description = "Maximum allowed upload size to Invoice Ninja.";
     };
 
+    msmtp = {
+      tls = lib.mkOption {
+        type = lib.types.bool;
+        default = true; 
+        description = "Enable SSL/TLS encryption";
+      };
+      from = lib.mkOption {
+        type = lib.types.str;
+        default = "";
+        description = "Email address message will come from.";
+      };
+      host = lib.mkOption {
+        type = lib.types.str;
+        default = "";
+        description = "SMTP host used to send mail.";
+      };
+      port = lib.mkOption {
+        type = lib.types.int;
+        default = 25;
+        description = "Port used to connect to SMTP host.";
+      };
+      username = lib.mkOption {
+        type = lib.types.str;
+        default = "";
+        description = "Username used to authenticate to SMTP host";
+      };
+      passwordeval = lib.mkOption {
+        type = lib.types.str;
+        default = "";
+        example = "cat /secrets/msmtp_password";
+        description = ''
+          A shell command to read the password from a secret file to avoid having it written in
+          the world-readable nix store. The password file must end with a newline (`\n`).
+        '';
+      };
+    };
+
     webserver = {
       caddy = {
         enable = lib.mkOption {
@@ -250,6 +306,8 @@ in
           APP_DEBUG = lib.mkDefault false;
           APP_URL = lib.mkDefault (url { hostName = cfg.hostName; });
           REACT_URL = lib.mkDefault (url { hostName = cfg.hostName; react = true; });
+          MAIL_MAILER = lib.mkDefault cfg.mailMailer;
+          MAIL_SENDMAIL_PATH = lib.mkDefault (if (cfg.mailMailer == "sendmail") then "${invoice-ninja-msmtp}/bin/msmtp" else "");
           DB_CONNECTION = lib.mkDefault "mysql";
           MULTI_DB_ENABLED = lib.mkDefault false;
           DEMO_MODE = lib.mkDefault false;
diff --git a/tests/test-config.nix b/tests/test-config.nix
index 6eef017..64f2a3f 100644
--- a/tests/test-config.nix
+++ b/tests/test-config.nix
@@ -10,6 +10,17 @@
 
   nixpkgs.config.allowUnfree = true;
 
+  environment.etc."msmtp-password" = {
+    enable = true;
+    user = "invoiceninja";
+    group = "invoiceninja";
+    mode = "0440";
+    text = ''
+      3t5h638t3a7y7275
+
+    '';
+  };
+
   users.users.test = {
     isNormalUser = true;
     extraGroups = [ "wheel" ];
@@ -19,6 +30,16 @@
   services.invoice-ninja = {
     enable = true;
     database.createLocally = true;
+    webserver.caddy.enable = true;
+    webserver.nginx.enable = false;
+    msmtp = {
+      tls = true;
+      from = "awkawb@awkawb.cloud";
+      host = "smtp.fastmail.com";
+      port = 465;
+      username = "awkawb@awkawb.cloud";
+      passwordeval = "cat /etc/msmtp-password";
+    };
     secretFile = ./test-secrets.env;
   };