我就是用这个，163,sina,都试过，发妹儿没问题。
const
BaseTable =
'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
function EncodeBase64(Source:string):string;
var
Times, LenSrc, i: Integer;
x1, x2, x3, x4: Char;
xt: Byte;
begin
Result := '';
LenSrc := Length(Source);
if LenSrc mod 3 = 0 then
Times := LenSrc div 3
else
Times := LenSrc div 3 + 1;
for i := 0 to Times - 1 do
begin
if LenSrc >= (3 + i * 3) then
begin
x1 := BaseTable[(ord(Source[1 + i * 3]) shr 2)+1];
xt := (ord(Source[1 + i * 3]) shl 4) and 48;
xt := xt or (ord(Source[2 + i * 3]) shr 4);
x2 := BaseTable[xt + 1];
xt := (Ord(Source[2 + i * 3]) shl 2) and 60;
xt := xt or (Ord(Source[3 + i * 3]) shr 6);
x3 := BaseTable[xt + 1];
xt := (ord(Source[3 + i * 3]) and 63);
x4 := BaseTable[xt + 1];
end
else if LenSrc >= (2 + i * 3) then
begin
x1 := BaseTable[(Ord(Source[1 + i * 3]) shr 2) + 1];
xt := (Ord(Source[1 + i * 3]) shl 4) and 48;
xt := xt or (Ord(Source[2 + i * 3]) shr 4);
x2 := BaseTable[xt + 1];
xt := (Ord(Source[2 + i * 3]) shl 2) and 60;
x3 := BaseTable[xt + 1];
x4 := '=';
end else
begin
x1 := BaseTable[(Ord(Source[1 + i * 3]) shr 2)+1];
xt := (Ord(Source[1 + i * 3]) shl 4) and 48;
x2 := BaseTable[xt + 1];
x3 := '=';
x4 := '=';
end;
Result := Result + x1 + x2 + x3 + x4;
end;
end;
在SMTP.OnConnect事件中写身份验证.
procedure TSendFile.NMSMTPConnect(Sender: TObject);
begin {身份验证}
if FSMTP.ReplyNumber = 250 then
FSMTP.Transaction('auth login');
if FSMTP.ReplyNumber = 334 then
begin
FSMTP.Transaction(EncodeBase64(FUserID));
FSMTP.Transaction(EncodeBase64(FPassword));
end;
end;
