public bool GetAttachmentFileStatus(int no)
{
if(_socket == (IntPtr)ErrorSocket) {
throw new InvalidOperationException();
}
if(no <= 0) {
throw new ArgumentOutOfRangeException();
}
SetHeaderSize();
_part_id = new StringBuilder(_header_size);
_part_no = Pop3GetAttachmentFileStatus(_socket, no, _part_id, _header_size);
if(_part_no > 0)
{
return true;
}
else
{
return false;
}
}