diff --git a/configuration.nix b/configuration.nix
index 0ddd9d95..d3f5ad96 100644
--- a/configuration.nix
+++ b/configuration.nix
@@ -7,13 +7,15 @@
 {
   imports =
     [ # Include the results of the hardware scan.
-      ./hardware-configuration.nix
       ./fs-configuration.nix
+      ./hardware-configuration.nix
+      ./net-configuration.nix
       ./services-conf/gitea-configuration.nix
       ./services-conf/jellyfin-configuration.nix
       ./services-conf/matrix-configuration.nix
       ./services-conf/nginx-configuration.nix
       ./services-conf/pleroma-configuration.nix
+      ./services-conf/postfix-configuration.nix
       ./services-conf/postgres-configuration.nix
       ./user-configuration.nix
     ];
@@ -24,12 +26,6 @@
     })
   ];
 
-  # TODO colin: re-enable the firewall
-  # networking.firewall.enable = false;
-  networking.firewall.allowedTCPPorts = [ 25 80 443 ];
-  # DLNA ports: https://jellyfin.org/docs/general/networking/index.html
-  networking.firewall.allowedUDPPorts = [ 1900 7359 ];
-
 
   # XXX colin: UNMODIFIED DEFAULTS BELOW
 
diff --git a/net-configuration.nix b/net-configuration.nix
new file mode 100644
index 00000000..52ec2771
--- /dev/null
+++ b/net-configuration.nix
@@ -0,0 +1,10 @@
+{ config, pkgs, ... }:
+
+{
+  networking.domain = "uninsane.org";
+
+  # networking.firewall.enable = false;
+  networking.firewall.allowedTCPPorts = [ 25 80 443 ];
+  # DLNA ports: https://jellyfin.org/docs/general/networking/index.html
+  networking.firewall.allowedUDPPorts = [ 1900 7359 ];
+}
diff --git a/services-conf/postfix-configuration.nix b/services-conf/postfix-configuration.nix
new file mode 100644
index 00000000..4a00ea9e
--- /dev/null
+++ b/services-conf/postfix-configuration.nix
@@ -0,0 +1,6 @@
+{ config, pkgs, lib, ... }:
+
+{
+  #services.postfix.enable = true;
+  services.postfix.hostname = "mx.uninsane.org";
+}
diff --git a/user-configuration.nix b/user-configuration.nix
index a03e9a5c..fe7f8eba 100644
--- a/user-configuration.nix
+++ b/user-configuration.nix
@@ -28,8 +28,10 @@
       pkgs.htop
       pkgs.matrix-synapse
       pkgs.mix2nix
+      pkgs.netcat
       pkgs.nmap
       pkgs.ripgrep
+      pkgs.telnet
       pkgs.sudo
       (pkgs.vim_configurable.customize {
         name = "vim";