(Delphi ActiveX) Reading Unread POP3 Email

The POP3 protocol does not provide the ability to ask the server which emails are "unread". Furthermore, a pure POP3 server does not even keep this information. Some servers, such as Exchange Server, expose both POP3 and IMAP interfaces. In these cases, information about read/unread status exists on the server, but it is only available via the IMAP protocol. Email clients such as Outlook and Thunderbird keep read/unread information on the client computer. This example demonstrates how UIDLs can be saved to track and read "unread" email.

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
mailman: TChilkatMailMan;
saSeenUidls: TCkStringArray;
success: Integer;
saUidls: ICkStringArray;
saUnseenUidls: TCkStringArray;
i: Integer;
n: Integer;
bundle: IChilkatEmailBundle;
email: IChilkatEmail;

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

// The mailman object is used for receiving (POP3) 
// and sending (SMTP) email.
mailman := TChilkatMailMan.Create(Self);

// Set the POP3 server's hostname
mailman.MailHost := 'pop.someMailServer.com';

// Set the POP3 login/password.
mailman.PopUsername := '***';
mailman.PopPassword := '***';

// You may keep a list of already-seen UIDLs in a text file:
// If this is the first time you're running this example,
// create an empty text file named "seenUidls.txt"
saSeenUidls := TCkStringArray.Create(Self);
success := saSeenUidls.LoadFromFile('seenUidls.txt');
if (success <> 1) then
  begin
    Memo1.Lines.Add('failed to load seenUidls.txt');
    Exit;
  end;

// Get the complete list of UIDLs on the mail server.
saUidls := mailman.GetUidls();
if (mailman.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(mailman.LastErrorText);
    Exit;
  end;

// Create a new string array object (it's an object, not an actual array)
// and add the UIDLs from saUidls that aren't already seen.
saUnseenUidls := TCkStringArray.Create(Self);

i := 0;
n := saUidls.Count;
while i < n do
  begin
    if (saSeenUidls.Contains(saUidls.GetString(i)) <> 1) then
      begin
        success := saUnseenUidls.Append(saUidls.GetString(i));
      end;
    i := i + 1;
  end;

if (saUnseenUidls.Count = 0) then
  begin
    Memo1.Lines.Add('No unseen emails!');

    Exit;
  end;

// Download in full the unseen emails:
bundle := mailman.FetchMultiple(saUnseenUidls.ControlInterface);
if (mailman.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(mailman.LastErrorText);

    Exit;
  end;

i := 0;
while i < bundle.MessageCount do
  begin
    email := bundle.GetEmail(i);
    Memo1.Lines.Add(email.From);
    Memo1.Lines.Add(email.Subject);
    Memo1.Lines.Add('----');

    i := i + 1;
  end;

// Save saUidls to "seenUidls.txt"
success := saUidls.SaveToFile('seenUidls.txt');
end;