function DecodeLine7Bit(Texto: String): String;
....
case Encoding of

'B':
begin

GetMem(Buffer, Length(Texto));
Size := DecodeLineBASE64(Texto, Buffer);
if Size>0 then //add by chenanyun
Buffer[Size] := #0;
Texto := String(Buffer);
FreeMem(Buffer); end;

'Q':
begin

while Pos('_', Texto) > 0 do
Texto[Pos('_', Texto)] := #32;

Texto := DecodeQuotedPrintable(Texto);
end;

'U':
begin

GetMem(Buffer, Length(Texto));
Size := DecodeLineUUCODE(Texto, Buffer);
if Size>0 then //fix by chenanyun
Buffer[Size] := #0;
Texto := String(Buffer);
FreeMem(Buffer);
end;
end;