code: def timestamp(self):
          
          # XXX ctime does not refer to creation time on POSIX systems, but
          # rather the last time the inode data changed. Source:
          # https://userprimary.net/posts/2007/11/18
          # /ctime-in-unix-means-last-change-time-not-create-time/
          if self.conf.time_source == CTIME:
              return os.path.getctime(self.path)
  
          # Fetch from the date header.
          return email.utils.mktime_tz(email.utils.parsedate_tz(
              self.message.get('Date')))
docs: Compute the normalized canonical timestamp of the mail.