#include 'array.au3'
$file=FileRead("C:\Documents and Settings\12\Рабочий стол\Косплей.eml")
$boun=StringRegExpReplace($file,'(?s).*?boundary="([^"]+)".*','\1')
$str=StringRegExp($file,'(?s)Content-Transfer-Encoding: base64\r\n\r\n(.*?)\r\n[-]*'&$boun,3)
$file=_Encoding_UTF8ToANSI(_Encoding_Base64Decode($str[0]))& @CRLF &_Encoding_UTF8ToANSI(_Encoding_Base64Decode($str[1]))
FileWrite(@ScriptDir&'\123.txt',$file)