(Delphi ActiveX) Using IMAP IDLE to Wait for Updates

This example demonstrates how to use the IMAP IDLE functionality in Chilkat.

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
imap: TChilkatImap;
success: Integer;
idleResultXml: WideString;

begin
imap := TChilkatImap.Create(Self);

// ....
// ....
// ....

// Select an IMAP mailbox
success := imap.SelectMailbox('INBOX');
if (success <> 1) then
  begin
    Memo1.Lines.Add(imap.LastErrorText);
    Exit;
  end;

// After a mailbox has been selected, IDLE may begin.
// Idling tells the IMAP server to push unsolicited updates for the selected
// mailbox to the connected client (which is your application).
success := imap.IdleStart();
if (success <> 1) then
  begin
    Memo1.Lines.Add(imap.LastErrorText);
    Exit;
  end;

// Once idling has started, your code still has to periodically check to see
// if any updates have arrived.  However, this is significantly different
// then what normally occurs when checking email.  The IdleCheck does NOT
// send a message to the IMAP server.  It simply checks the connection to see
// if any data has arrived.  If so, it can be consumed and the client (your app)
// can react appropriately.  

// Note: It is recommended that idling only run for a max of 20 minutes before stopping and
// re-starting the IDLE.  This is to maintain a minimum low level of activity so that 
// the IMAP server does not disconnect (which it may do if it considers the connection to 
// be truly inactive, i.e. forgotten).

// To check the connection for IDLE updates, call IdleCheck.  The 1st argument indicates how
// long we're willing to wait. We'll wait 1 millisecond:

idleResultXml := imap.IdleCheck(1);
if (imap.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add(imap.LastErrorText);
    Exit;
  end;

// See the online reference documentation for details regarding the XML that is returned.
// Your application code would parse the XML to determine what action to take.
// If the XML contains "<idle></idle>", then no updates are available and your application
// would call IdleCheck again at some point in the future.

// If updates are available, the IDLE must be terminated by calling IdleDone, like this:
success := imap.IdleDone();
if (success <> 1) then
  begin
    Memo1.Lines.Add(imap.LastErrorText);
    Exit;
  end;

// Once the IDLE is terminated, your application can make calls to fetch email, etc.
// Any attempt to communicate with the IMAP server prior to terminating the IDLE will
// result in failure.

// IMPORTANT: Please realize that your application code will be structured differently than shown here.
// The call to IdleCheck will likely be in a function/procedure that is periodically called
// after the IdleStart has been called from some other location in your app
end;