feat(mail): Import email configuration into Nix

This moves my email configuration into NixOS, including the following
features:

1. Replaced the NixOS-builtin offlineimap user service with a custom
   one that runs notmuch-indexing as part of the systemd unit instead
   of a postsynchook, which is significantly more reliable.
2. Adds configuration for notmuch and its tagging.
3. Adds configuration for OfflineIMAP & MSMTP.

Relevant emacs configuration has also been added to my emacs.d
repository.

1 files changed, 3 insertions, 8 deletions

diff --git a/configuration.nix b/configuration.nix
index de8fcdd395..e4a9574292 100644
--- a/configuration.nix
+++ b/configuration.nix
@@ -7,11 +7,12 @@
 {
   imports =
     [
+    ./desktop.nix
+    ./dotfiles.nix
     ./hardware-configuration.nix
     ./local-configuration.nix
+    ./mail.nix
     ./packages.nix
-    ./desktop.nix
-    ./dotfiles.nix
     ];
 
   # Use the systemd-boot EFI boot loader.
@@ -61,12 +62,6 @@
   # Enable GNOME keyring (required for Evolution)
   services.gnome3.gnome-keyring.enable = true;
 
-  # Enable OfflineIMAP (configuration itself is user-data)
-  services.offlineimap = {
-    install = true;
-    path    = with pkgs; [ pass notmuch ];
-  };
-
   virtualisation = {
     # Configure Docker (with socket activation):
     # Side note: ... why is this in virtualisation? ...