Использование SMTP Relay Server

Использование SMTP Relay Server - отсылка письма напрямую минуя любые промежуточные сервера (пример взят из библиотеки Indy). Для отсылки письма с использованием компонентов Indy. Пример для Delphi 7 (скорее всего будет работать и в Delphi 6), для Kylix 3 нужны небольшие исправления для перевода в CLX приложение (сама функциональность та же).

Пример модуля:

unit fMain;
 

 
 
interface
 
uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  IdTCPConnection, IdTCPClient, IdMessageClient, IdSMTP, IdComponent,
  IdUDPBase, IdUDPClient, IdDNSResolver, IdBaseComponent, IdMessage,
  StdCtrls, ExtCtrls, ComCtrls, IdAntiFreezeBase, IdAntiFreeze;
 
type
  TfrmMain = class(TForm)
    IdMessage: TIdMessage;
    IdDNSResolver: TIdDNSResolver;
    IdSMTP: TIdSMTP;
    Label1: TLabel;
    sbMain: TStatusBar;
    Label2: TLabel;
    edtDNS: TEdit;
    Label3: TLabel;
    Label4: TLabel;
    edtSender: TEdit;
    Label5: TLabel;
    edtRecipient: TEdit;
    Label6: TLabel;
    edtSubject: TEdit;
    Label7: TLabel;
    mmoMessageText: TMemo;
    btnSendMail: TButton;
    btnExit: TButton;
    IdAntiFreeze: TIdAntiFreeze;
    Label8: TLabel;
    edtTimeOut: TEdit;
    Label9: TLabel;
    Label10: TLabel;
    procedure btnExitClick(Sender: TObject);
    procedure btnSendMailClick(Sender: TObject);
  public
  fMailServers : TStringList;
  Function PadZero(s:String):String;
  Function GetMailServers:Boolean;
  Function ValidData : Boolean;
  Procedure SendMail; OverLoad;
  Function SendMail(aHost : String):Boolean; OverLoad;
  Procedure LockControls;
  procedure UnlockControls;
  Procedure Msg(aMessage:String);
  end;
 
var
  frmMain: TfrmMain;
 
implementation
 
{$R *.DFM}
 
procedure TfrmMain.btnExitClick(Sender: TObject);
begin
application.terminate;
end;
 
procedure TfrmMain.btnSendMailClick(Sender: TObject);
begin
Msg('');
LockControls;
if ValidData then SendMail;
UnlockControls;
Msg('');
end;
 
function TfrmMain.GetMailServers: Boolean;
var
  i,x : integer;
  LDomainPart : String;
  LMXRecord : TMXRecord;
begin
if not assigned(fmailServers) then fMailServers := TStringList.Create;
fmailServers.clear;
  Result := true;
  with IdDNSResolver do
  begin
  QueryResult.Clear;
  QueryRecords := [qtMX];
  Msg('Setting up DNS query parameters');
  Host := edtDNS.text;
  ReceiveTimeout := StrToInt(edtTimeOut.text);
  // Extract the domain part from recipient email address
  LDomainPart := copy(edtRecipient.text,pos('@',edtRecipient.text)+1,length(edtRecipient.text)); 
  // the domain name to resolve
  try
  Msg('Resolving DNS');
  Resolve(LDomainPart);
  if QueryResult.Count > 0 then
    begin
      for i := 0 to QueryResult.Count - 1 do
        begin
        LMXRecord := TMXRecord(QueryResult.Items[i]);
        fMailServers.Append(PadZero(IntToStr(LMXRecord.Preference)) + '=' + LMXRecord.ExchangeServer);
        end;
    // sort in order of priority and then remove extra data
    fMailServers.Sorted := false;
    for i := 0 to fMailServers.count - 1 do
      begin
      x := pos('=',fMailServers.Strings[i]);
      if x > 0 then fMailServers.Strings[i] :=
        copy(fMailServers.Strings[i],x+1,length(fMailServers.Strings[i]));
      end;
    fMailServers.Sorted := true;
    fMailServers.Duplicates := dupIgnore;
    Result := true;
    end
  else
    begin
    Msg('No response from DNS server');
    MessageDlg('There is no response from the DNS server !', mtInformation, [mbOK], 0);
    Result := false;
    end;
  except
  on E : Exception do
    begin
    Msg('Error resolving domain');
    MessageDlg('Error resolving domain: ' + e.message, mtInformation, [mbOK], 0);
    Result := false;
    end;
  end;
  end;
end;
 
// Used in DNS preferance sorting
procedure TfrmMain.LockControls;
var i : integer;
begin
edtDNS.enabled := false;
edtSender.enabled := false;
edtRecipient.enabled := false;
edtSubject.enabled := false;
mmoMessageText.enabled := false;
btnExit.enabled := false;
btnSendMail.enabled := false;
end;
 
procedure TfrmMain.UnlockControls;
begin
edtDNS.enabled := true;
edtSender.enabled := true;
edtRecipient.enabled := true;
edtSubject.enabled := true;
mmoMessageText.enabled := true;
btnExit.enabled := true;
btnSendMail.enabled := true;
end;
 
 
function TfrmMain.PadZero(s: String): String;
begin
if length(s) < 2 then s := '0' + s;
Result := s;
end;
 
procedure TfrmMain.SendMail;
var i : integer;
begin
if GetMailServers then
  begin
  with IdMessage do
    begin
    Msg('Assigning mail message properties');
    From.Text := edtSender.text;
    Sender.Text := edtSender.text;
    Recipients.EMailAddresses := edtRecipient.text;
    Subject := edtSubject.text;
    Body := mmoMessageText.Lines;
    end;
  for i := 0 to fMailServers.count -1 do
    begin
    Msg('Attempting to send mail');
    if SendMail(fMailServers.Strings[i]) then
      begin
      MessageDlg('Mail successfully sent and available for pickup by recipient !', 
mtInformation, [mbOK], 0);
      Exit;
      end;
    end;
  // if we are here then something went wrong .. ie there were no available servers to accept our mail!
  MessageDlg('Could not send mail to remote server - please try again later.', mtInformation, [mbOK], 0);
  end;
if assigned(fMailServers) then FreeAndNil(fMailServers);
end;
 
function TfrmMain.SendMail(aHost: String): Boolean;
begin
Result := false;
with IdSMTP do
  begin
  Caption := 'Trying to sendmail via: ' + aHost;
  Msg('Trying to sendmail via: ' + aHost);
  Host := aHost;
  try
  Msg('Attempting connect');
  Connect;
  Msg('Successful connect ... sending message');
  Send(IdMessage);
  Msg('Attempting disconnect');
  Disconnect;
  msg('Successful disconnect');
  Result := true;
  except on E : Exception do
    begin
    if connected then try disconnect; except end;
    Msg('Error sending message');
    result := false;
    ShowMessage(E.Message);
    end;
  end;
  end;
Caption := '';
end;
 
 
function TfrmMain.ValidData: Boolean;
var ErrString:string;
begin
Result := True;
ErrString := '';
if trim(edtDNS.text) = '' then ErrString := ErrString +  #13 + #187 + 'DNS server not filled in';
if trim(edtSender.text) = '' then ErrString := ErrString + #13 + #187 + 'Sender email not filled in';
if trim(edtRecipient.text) = '' then ErrString := ErrString +  #13 + #187 + 'Recipient not filled in';
if ErrString <> '' then
  begin
  MessageDlg('Cannot proceed due to the following errors:'+#13+#10+ ErrString, mtInformation, [mbOK], 0);
  Result := False;
  end;
end;
 
procedure TfrmMain.Msg(aMessage: String);
begin
sbMain.SimpleText := aMessage;
application.ProcessMessages;
end;
 
end.

Форма для модуля:

object frmMain: TfrmMain
  Left = 243
  Top = 129
  Width = 448
  Height = 398
  Caption = 'INDY - SMTP Relay Demo'
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'MS Sans Serif'
  Font.Style = []
  OldCreateOrder = False
  PixelsPerInch = 96
  TextHeight = 13
  object Label1: TLabel
    Left = 7
    Top = 8
    Width = 311
    Height = 26
    Caption = 
      'Demonstrates sending mail directly to a users mailbox on a remot' +
      'e mailserver - this negates the need for a local SMTP server'
    Font.Charset = DEFAULT_CHARSET
    Font.Color = clGray
    Font.Height = -11
    Font.Name = 'MS Sans Serif'
    Font.Style = []
    ParentFont = False
    WordWrap = True
  end
  object Label2: TLabel
    Left = 8
    Top = 64
    Width = 111
    Height = 13
    Caption = 'DNS server IP address:'
  end
  object Label3: TLabel
    Left = 8
    Top = 123
    Width = 104
    Height = 13
    Caption = 'Sender email address:'
  end
  object Label4: TLabel
    Left = 288
    Top = 64
    Width = 49
    Height = 13
    Caption = 'Required !'
    Font.Charset = DEFAULT_CHARSET
    Font.Color = clGray
    Font.Height = -11
    Font.Name = 'MS Sans Serif'
    Font.Style = []
    ParentFont = False
  end
  object Label5: TLabel
    Left = 8
    Top = 150
    Width = 115
    Height = 13
    Caption = 'Recipient email address:'
  end
  object Label6: TLabel
    Left = 8
    Top = 177
    Width = 72
    Height = 13
    Caption = 'Subject of mail:'
  end
  object Label7: TLabel
    Left = 8
    Top = 204
    Width = 66
    Height = 13
    Caption = 'Message text:'
  end
  object Label8: TLabel
    Left = 8
    Top = 91
    Width = 95
    Height = 13
    Caption = 'DNS server timeout:'
  end
  object Label9: TLabel
    Left = 336
    Top = 124
    Width = 49
    Height = 13
    Caption = 'Required !'
    Font.Charset = DEFAULT_CHARSET
    Font.Color = clGray
    Font.Height = -11
    Font.Name = 'MS Sans Serif'
    Font.Style = []
    ParentFont = False
  end
  object Label10: TLabel
    Left = 336
    Top = 148
    Width = 49
    Height = 13
    Caption = 'Required !'
    Font.Charset = DEFAULT_CHARSET
    Font.Color = clGray
    Font.Height = -11
    Font.Name = 'MS Sans Serif'
    Font.Style = []
    ParentFont = False
  end
  object sbMain: TStatusBar
    Left = 0
    Top = 352
    Width = 440
    Height = 19
    Panels = <>
  end
  object edtDNS: TEdit
    Left = 128
    Top = 60
    Width = 153
    Height = 21
    TabOrder = 1
  end
  object edtSender: TEdit
    Left = 128
    Top = 119
    Width = 205
    Height = 21
    TabOrder = 2
  end
  object edtRecipient: TEdit
    Left = 128
    Top = 146
    Width = 205
    Height = 21
    TabOrder = 3
  end
  object edtSubject: TEdit
    Left = 128
    Top = 173
    Width = 205
    Height = 21
    TabOrder = 4
  end
  object mmoMessageText: TMemo
    Left = 128
    Top = 200
    Width = 205
    Height = 113
    TabOrder = 5
  end
  object btnSendMail: TButton
    Left = 258
    Top = 321
    Width = 75
    Height = 25
    Caption = 'Send mail !'
    TabOrder = 6
    OnClick = btnSendMailClick
  end
  object btnExit: TButton
    Left = 356
    Top = 8
    Width = 75
    Height = 25
    Caption = 'E&xit'
    TabOrder = 7
    OnClick = btnExitClick
  end
  object edtTimeOut: TEdit
    Left = 128
    Top = 87
    Width = 61
    Height = 21
    TabOrder = 8
    Text = '5000'
  end
  object IdMessage: TIdMessage
    AttachmentEncoding = 'MIME'
    BccList = <>
    CCList = <>
    Encoding = meMIME
    Recipients = <>
    ReplyTo = <>
    Left = 12
    Top = 236
  end
  object IdDNSResolver: TIdDNSResolver
    Port = 53
    ReceiveTimeout = 60
    QueryRecords = []
    Left = 12
    Top = 268
  end
  object IdSMTP: TIdSMTP
    MaxLineAction = maException
    ReadTimeout = 0
    Port = 25
    AuthenticationType = atNone
    Left = 12
    Top = 204
  end
  object IdAntiFreeze: TIdAntiFreeze
    Left = 12
    Top = 300
  end
end

Автор: Vit

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