suggestion.clj

(def spreadsheet-regex
  #"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet")

(defn content-type-spreadsheet? [content-type]
  (when content-type
    (re-find spreadsheet-regex content-type)))

(defn has-spreadsheet? [msg]
  (and (:multipart? msg)
       (some content-type-spreadsheet?
             (map :content-type (:body msg)))))