Use Sendico SMTP mailbox for local notifications (#57)

infra/local/scripts/test.sh

@@ -29,6 +29,10 @@ if images >/dev/null 2>&1; then fail 'Offline resolution succeeded'; fi
 [ "$(cat "$STATE/images.env")" = 'previous build' ] || fail 'Failed resolution replaced pins'
 if printf '{"api_key":"","sender_address":"notifications@localhost.test"}' | email_valid; then fail 'Empty email accepted'; fi
 printf '{"api_key":"fixture-only","sender_address":"sender@example.test"}' | email_valid
+printf '{"password":"fixture-only"}' | smtp_valid
+for invalid in '{"password":""}' '{"password":"bad\nvalue"}' '{"password":"bad\u0000value"}' '{"password":"fixture","username":"not-a-secret"}'; do
+ if printf '%s' "$invalid" | smtp_valid; then fail 'Invalid SMTP secret accepted'; fi
+done
 # Initialized Vault without matching local keys must fail without initializing it again.
 vault() { printf '{"initialized":true}'; }
 if (initialize) > "$WORK/initialize-error" 2>&1; then fail 'Missing local keys accepted'; fi