(Delphi ActiveX) How to Download Messages in MessageSet One at a Time

If a message set contains a huge number of emails, it's NOT a good idea to try to download all at once into an email bundle using a method such as FetchBundle. It's better to iterate over the messages in the set to download one by one.

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat for Delphi Downloads Chilkat ActiveX DLL for Delphi Chilkat non-ActiveX DLL for Delphi * The examples here use the ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Integer;
imap: TChilkatImap;
fetchUids: Integer;
messageSet: TMessageSet;
email: TChilkatEmail;
i: Integer;

begin
success := 0;

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

imap := TChilkatImap.Create(Self);

// Connect using TLS.
imap.Ssl := 1;
imap.Port := 993;
success := imap.Connect('imap.example.com');
if (success = 0) then
  begin
    Memo1.Lines.Add(imap.LastErrorText);
    Exit;
  end;

// Authenticate
success := imap.Login('email_account_login','email_account_password');
if (success = 0) then
  begin
    Memo1.Lines.Add(imap.LastErrorText);
    Exit;
  end;

// Select an IMAP mailbox
success := imap.SelectMailbox('Inbox');
if (success = 0) then
  begin
    Memo1.Lines.Add(imap.LastErrorText);
    Exit;
  end;

// Search for messages and return a set of matching messages.
// (This example will simply search for ALL messages.)
fetchUids := 1;

messageSet := TMessageSet.Create(Self);
success := imap.QueryMbx('ALL',fetchUids,messageSet.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(imap.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Number of messages = ' + IntToStr(messageSet.Count));

email := TChilkatEmail.Create(Self);
i := 0;
while i < messageSet.Count do
  begin
    success := imap.FetchEmail(0,messageSet.GetId(i),fetchUids,email.ControlInterface);
    if (success = 0) then
      begin
        Memo1.Lines.Add(imap.LastErrorText);
        Exit;
      end;

    Memo1.Lines.Add(email.From + '; ' + email.Subject);

    i := i + 1;
  end;

Memo1.Lines.Add('OK');
end;