func sizeAndHashOf(p gmime.Part) (int, string) {
dataWrapper := p.ContentObject()
memStream := gmime.NewMemStream()
c := dataWrapper.WriteToStream(memStream)
memStream.Flush()
data := memStream.Bytes()
hasher := md5.New()
hasher.Write(data)
hashString := hex.EncodeToString(hasher.Sum(nil))
return int(c), hashString
}
