I am grateful to receive a lot of feedback from people on the Internet. Thank you very much. You definitely improved the paper and my knowledge. From Peter Galbraith (pointed me on mh-e) Jerrad Pierce (explained good points for pick and mh-e, and discussion on IMAP) Steve Rader (valuable discussion on and help with MIME and charset encodings) From Andrew Antle (exceptionally comprehensive help with the English language) Christophe-Marie Duquesne (nice and motivating words) John Litborn (positive feedback, and nice chatting about German language) Dieter Plaetinck (very sophisticated feedback) meillo