※ Attachable extensions are as follows and can be up to 10MB. Picture files (tipg. jpeg. gif. png. bmp) ) Video file (mkv, mp4. m4v, flv. avi, wmv) Sound files (mp3. m4a wavy ) Compressed files (zip. alz. egg) Document files (hwp. hwpx, doc. docx, xls, xlsx, ppt. pptx, pdf. txt)