+* libxapian (C++, full text search)
+* libgmime (C, glib, RFC822+MIME library)
+* libnotmuch (C and C++)
+* /usr/bin/notmuch (C)
+* GnuPG (C)
+* Emacs UI (emacs lisp)
+ * notmuch-emacs
+ * mml-mode
+* Alot / nmbug / nmbug-status (python)
+ * python-bindings