使用 TIde IMAP4.UID RetrieveTextPeek2() 检索电子邮件的消息正文时出现错误字符

Question

在我的应用程序（Windows 10、Delphi 10.4）中，我使用TIdIMAP4 通过以下代码从服务器检索电子邮件正文：

var aBody : string := '';
UIDRetrieveTextPeek2(MsgID,aBody);

如果返回的字符串以<!DOCTYPE html>'#$D#$A'<html lang="en" xmlns="http://www.w3.org/1999/xhtml" xmlns:o="urn:schemas-microsoft-com:...开头

或

<html><head><style type="text/css">'#$D#$A'@media screen and (max-width:480px) {'#$D#$A' .background_inner {'#$D#$A' padding: 0!important;'#$D#$A'....

我可以看到正确形成的 HTML 内容，但是当它开始时：

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.='#$D#$A'w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">=0A<html xmlns=3D"http://www.='#$D#$A'w3.org/1999/xhtml"><head><style type=3D"text/css" media=3D"all">=0A=09a:hov='#$D#$A'er {=09color: red;=09}=0A=09a {=0A=09=09text-decoration: underline;=0A=09='#$D#$A'=09color: #0088cc;=0A=09}....

HTML 格式错误 (=0A=09a:hov='#$D#$A'er {=09color: red;=09}=0A=09a {=0A=09=09text-decoration: underline;=0A=09=)

我能做些什么来解决它？

更新

这是一个可重现的例子：

unit Unit11;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls,
  IdIMAP4,IdMessage,IdSSLOpenSSL,IdExplicitTLSClientServerBase, IdBaseComponent, IdIntercept, IdLogBase, IdLogFile;

type
  TForm11 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form11: TForm11;

implementation

{$R *.dfm}

procedure TForm11.Button1Click(Sender: TObject);
var SearchInfo: array of TIdIMAP4SearchRec;
    IdMessage1: TIdMessage;
    IdSSLIOHandlerSocketOpenSSL1: TIdSSLIOHandlerSocketOpenSSL;
    i, msgs : integer;
    MsgID, aBody : string;
begin
    with TIdIMAP4.create do try
        IdSSLIOHandlerSocketOpenSSL1 := TIdSSLIOHandlerSocketOpenSSL.Create(nil);
        IdSSLIOHandlerSocketOpenSSL1.SSLOptions.Method := sslvSSLv23;
        IOhandler := IdSSLIOHandlerSocketOpenSSL1;
        authType := iatUserPass;
        Host := 'imap.gmail.com';
        userName := 'xxxxxxxxxx';
        password := 'yyyyyyyyyy';
        UseTLS := utUseImplicitTLS;
        if Connect(TRUE) then
        try
            SelectMailBox('INBOX');
            SetLength(SearchInfo, 1);
            SearchInfo[0].SearchKey := skAll;
            if SearchMailBox(SearchInfo)
            and (High(MailBox.SearchResult) > -1) then
            try
                msgs := High(MailBox.SearchResult)+1;

                for i := 0 to msgs - 1 do
                begin
                    MsgID := '';
                    GetUID(MailBox.SearchResult[i], MsgID);
                    // some bodyies are unreadable, some ok and some as the following are unencoded QP
                    if MsgID = '16805' then begin
                        var IdLogFile1: TIdLogFile := TIdLogFile.Create(nil);
                        IdLogFile1.Filename := 'log.txt';
                        intercept := IdLogFile1;
                        IdLogFile1.Active := TRUE;
                        UIDRetrieveTextPeek2(MsgID,aBody);
                        IdLogFile1.Active := FALSE;
                        IdLogFile1.Free;
                    end;
                end;
            finally

            end;
        finally

        end;
    finally
        IdSSLIOHandlerSocketOpenSSL1.free;
    end;
end;

end.

及其捕获的日志：

Sent 26/7/2021 10:09:45 ??: C55 UID FETCH 16805 (BODYSTRUCTURE)<EOL>
Recv 26/7/2021 10:09:45 ??: * 51 FETCH (UID 16805 BODYSTRUCTURE (("TEXT" "PLAIN" ("CHARSET" "utf-8") NIL NIL "8BIT" 760 16 NIL NIL NIL)("TEXT" "HTML" ("CHARSET" "utf-8") NIL NIL "QUOTED-PRINTABLE" 3962 80 NIL NIL NIL) "ALTERNATIVE" ("BOUNDARY" "----=_NextPart_000_0008_01D583AF.54009F20") NIL NIL))<EOL>
Recv 26/7/2021 10:09:45 ??: C55 OK Success<EOL>
Sent 26/7/2021 10:09:45 ??: C56 UID FETCH 16805 (BODY.PEEK[2])<EOL>
Recv 26/7/2021 10:09:46 ??: * 51 FETCH (UID 16805 BODY[2] 
Recv 26/7/2021 10:09:46 ??: {3962}<EOL>
Recv 26/7/2021 10:09:46 ??: <html><EOL>    <head><EOL>  <style type=3D"text/css"><EOL>            body, td, span, p, th { font-size: 11px; }<EOL>       table.html-email {margin:10px auto;background:#fff;border:solid =<EOL>#dad8d8 1px;}<EOL>        .html-email tr{border-bottom : 1px solid #eee;}<EOL>        span.grey {color:#666;}<EOL>        span.date {color:#666;font-size: 10px;}<EOL>        a.default:link, a.default:hover, a.default:visited =<EOL>{color:#666;line-height:25px;background: #f2f2f2;margin: 10px ;padding: =<EOL>3px 8px 1px 8px;border: solid #CAC9C9 1px;border-radius: =<EOL>4px;-webkit-border-radius: 4px;-moz-border-radius: 4px;text-shadow: 1px =<EOL>1px 1px #f2f2f2;font-size: 12px;background-position: 0px 0px;display: =<EOL>inline-block;text-decoration: none;}<EOL>       a.default:hover {color:#888;background: #f8f8f8;}<EOL>      .cart-summary{ }<EOL>       .html-email th { background: #ccc;margin: 0px;padding: 10px;}<EOL>      .sectiontableentry2, .html-email th, .cart-summary th{ background: =<EOL>#ccc;margin: 0px;padding: 10px;}<EOL>      .sectiontableentry1, .html-email td, .cart-summary td {background: =<EOL>#fff;margin: 0px;padding: 10px;}<EOL>  </style><EOL><EOL>    </head><EOL><EOL>    <body style=3D"background: #F2F2F2;word-wrap: break-word;"><EOL> <div style=3D"background-color: #e6e6e6;" width=3D"100%"><EOL>      <table style=3D"margin: auto;" cellpadding=3D"0" cellspacing=3D"0"  =<EOL>><EOL>        <tr><EOL>           <td><EOL>           <table width=3D"100%" border=3D"0" cellpadding=3D"0" =<EOL>cellspacing=3D"0" class=3D"html-email"><EOL>             <tr><EOL>               <td ><EOL><EOL>                 =CE=9A=CE=B1=CE=BB=CF=8E=CF=82 =<EOL>=CE=AE=CF=81=CE=B8=CE=B1=CF=84=CE=B5 =CF=83=CF=84=CE=BF =<EOL>=CE=91=CE=A1=CE=93=CE=A5=CE=A1=CE=A9 =<EOL>=CE=A0=CE=91=CE=A0=CE=91=CE=93=CE=95=CE=A9=CE=A1=CE=93=CE=99=CE=9F=CE=A5  =<EOL>              <br /><EOL>                                 </td><EOL>              </tr><EOL>          </table><EOL><EOL>          <table class=3D"html-email" cellspacing=3D"0" cellpadding=3D"0" =<EOL>border=3D"0" width=3D"100%"><EOL>             <tr><EOL>               <th width=3D"100%"><EOL>                    =CE=A4=CE=B1 =CF=83=CF=84=CE=BF=CE=B9=CF=87=CE=B5=CE=AF=CE=B1 =<EOL>=CF=84=CE=B7=CF=82 =CE=B5=CE=B3=CE=B3=CF=81=CE=B1=CF=86=CE=AE=CF=82 =<EOL>=CF=83=CE=B1=CF=82                </th><EOL><EOL>             </tr><EOL>              <tr><EOL>               <td valign=3D"top" width=3D"100%"><EOL>                 =CE=8C=CE=BD=CE=BF=CE=BC=CE=B1 =<EOL>=CF=83=CF=8D=CE=BD=CE=B4=CE=B5=CF=83=CE=B7=CF=82dpap<br />=CE=A4=CE=BF =<EOL>=CF=8C=CE=BD=CE=BF=CE=BC=CE=B1 =CF=80=CE=BF=CF=85 =<EOL>=CE=B5=CE=BC=CF=86=CE=B1=CE=BD=CE=AF=CE=B6=CE=B5=CF=84=CE=B1=CE=B9: =<EOL>=CE=91=CE=A1=CE=93=CE=A5=CE=A1=CE=A9 =<EOL>=CE=A0=CE=91=CE=A0=CE=91=CE=93=CE=95=CE=A9=CE=A1=CE=93=CE=99=CE=9F=CE=A5<=<EOL>br />O =CE=BA=CF=89=CE=B4=CE=B9=CE=BA=CF=8C=CF=82 =<EOL>=CF=83=CE=B1=CF=82staran<br /><br />=CE=97 =<EOL>=CE=B4=CE=B9=CE=B5=CF=8D=CE=B8=CF=85=CE=BD=CF=83=CE=B7 =<EOL>=CF=83=CE=B1=CF=82: <br />E-Mail: dpapdpap@gmail.com<br =<EOL>/>=CE=A0=CF=81=CE=BF=CE=B2=CE=B1=CE=BB=CE=BB=CF=8C=CE=BC=CE=B5=CE=BD=CE=BF=<EOL> =CF=8C=CE=BD=CE=BF=CE=BC=CE=B1: =CE=91=CE=A1=CE=93=CE=A5=CE=A1=CE=A9 =<EOL>=CE=A0=CE=91=CE=A0=CE=91=CE=93=CE=95=CE=A9=CE=A1=CE=93=CE=99=CE=9F=CE=A5<=<EOL>br />=CE=9F=CE=BD=CE=BF=CE=BC=CE=B1 =<EOL>=CE=B5=CF=84=CE=B1=CE=B9=CF=81=CE=AF=CE=B1=CF=82: =<EOL>=CE=91.=CE=94.=CE=A0=CE=91=CE=A0=CE=91=CE=93=CE=95=CE=A9=CE=A1=CE=93=CE=99=<EOL>=CE=9F=CE=A5<br />=CE=9F=CE=BD=CE=BF=CE=BC=CE=B1: =<EOL>=CE=91=CE=A1=CE=93=CE=A5=CE=A1=CE=A9<br =<EOL>/>=CE=95=CF=80=CE=AF=CE=B8=CE=B5=CF=84=CE=BF: =<EOL>=CE=A0=CE=91=CE=A0=CE=91=CE=93=CE=95=CE=A9=CE=A1=CE=93=CE=99=CE=9F=CE=A5<=<EOL>br />=CE=94=CE=B9=CE=B5=CF=8D=CE=B8=CF=85=CE=BD=CF=83=CE=B7 1: =<EOL>=CE=A6=CE=95=CE=99=CE=94=CE=99=CE=A0=CE=A0=CE=99=CE=94=CE=9F=CE=A5 2<br =<EOL>/>=CE=A4=CE=B1=CF=87. =CE=BA=CF=89=CE=B4=CE=B9=CE=BA=CF=8C=CF=82: =<EOL>32131<br />=CE=A0=CF=8C=CE=BB=CE=B7: =<EOL>=CE=9B=CE=99=CE=92=CE=91=CE=94=CE=95=CE=99=CE=91<br =<EOL>/>=CE=A7=CF=8E=CF=81=CE=B1: Greece<br />=CE=9D=CE=BF=CE=BC=CF=8C=CF=82 / =<EOL>=CE=A0=CE=B5=CF=81=CE=B9=CE=BF=CF=87=CE=AE: =<EOL>=CE=92=CE=9F=CE=99=CE=A9=CE=A4=CE=99=CE=91=CE=A3<br =<EOL>/>=CE=A4=CE=B7=CE=BB.: 2261089120<br />=CE=BA=CE=B9=CE=BD.: =<EOL>6974398860<br />               </td><EOL>              </tr><EOL>          </table><EOL>           </td><EOL>      </tr><EOL>      </table><EOL>   </div><EOL>    </body><EOL></html><EOL><EOL>
Recv 26/7/2021 10:09:46 ??: )<EOL>
Recv 26/7/2021 10:09:46 ??: C56 OK Success<EOL>

Answer 1

TIdIMAP4.UIDRetrieveTextPeek2() 首先检索电子邮件的正文结构，然后扫描它以查找报告的第一个非零大小的文本部分。如果没有找到，则使用最后一个文本部分。然后它使用所选部分的指定字节编码和字符集来解码该部分的文本以进行输出。

无论如何，至少理论上是这样的。

在您的日志中，有问题的电子邮件包含 IMAP 服务器报告的 2 个文本部分：

• text/plain，大小 760，编码 "8BIT"，字符集 "utf-8"
• text/html，大小 3962，编码 "QUOTED-PRINTABLE"，字符集 "utf-8"

但是，在 cmets 中，您说 UIDRetrieveStructure()（UIDRetrieveTextPeek2() 在内部使用）实际上是在报告 3 个文本部分：

• multipart/alternative
• text/plain，大小 760，编码 "8BIT"，字符集 "utf-8"
• text/html，大小 3962，编码 "QUOTED-PRINTABLE"，字符集 "utf-8"

您的日志显示UIDRetrieveTextPeek2() 正在检索BODY.PEEK[2]，因此它认为它正在请求text/plain 部分的内容（这是有道理的，因为这是第一个非空文本部分），但 实际上 请求的是 text/html 部分的内容。这将不得不解决。我已经为此开了一张票：

#368 TIdIMAP4.InternalRetrieveText() does not retreive text correctly

由于text/plain 部分的字节编码是8bit，UIDRetrieveTextPeek2() 不会尝试解码 HTML 中的 QP 编码字符，这就解释了为什么您会看到它们（=0A、=3D 、=09 等）在输出 string 中。