Add make rule to init mu database

Makefile

@@ -1,4 +1,4 @@
-.PHONY: test build
+.PHONY: test build mu davmail all
 
 test:
 	sudo nixos-rebuild test --flake .
@@ -6,8 +6,21 @@ test:
 build:
 	sudo nixos-rebuild build --flake .
 
+mu:
+	mu init --maildir ~/.mail \
+		--my-address=e.litherlandsmith@proton.me \
+		--my-address=evie@xenia.me.uk \
+		--my-address=evie@litherlandsmith.slmail.me \
+		--my-address=e.litherlandsmith@icloud.com \
+		--my-address=evie.litherland-smith@ukaea.uk \
+		--my-address=elitherl@jet.uk
+
 extra/davmail.properties:
 	touch $@
 
 ~/.davmail.properties: extra/davmail.properties
 	cp $? $@
+
+davmail: ~/.davmail.properties
+
+all: test mu davmail