Delphi DLL

Fetch a Chunk of Messages, Tracking Failures

Demonstrates the Chilkat Imap.FetchChunk2 method, which downloads a run of messages by sequence number and reports which succeeded and which failed. The arguments are the starting sequence number, the count, a MessageSet that receives the failed IDs, a MessageSet that receives the successfully-fetched IDs, and the EmailBundle. This example fetches the first chunk of messages and reports the success and failure counts.

Background: When bulk-downloading a large mailbox, individual messages can occasionally fail to fetch (a corrupt message on the server, a transient error) without failing the whole operation. FetchChunk2 is designed for that reality: it returns a partial EmailBundle plus two MessageSet objects so your code can log or retry exactly the messages that did not come through, rather than aborting the entire sync.

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var
success: Boolean;
imap: HCkImap;
numMessages: Integer;
count: Integer;
failedSet: HCkMessageSet;
fetchedSet: HCkMessageSet;
bundle: HCkEmailBundle;

begin
success := False;

//  Demonstrates the Imap.FetchChunk2 method, which downloads a run of messages by sequence
//  number and reports which succeeded and which failed.  The 1st argument is the starting
//  sequence number, the 2nd is the count, the 3rd receives the failed IDs, the 4th receives
//  the successfully-fetched IDs, and the 5th is the EmailBundle.

imap := CkImap_Create();

CkImap_putSsl(imap,True);
CkImap_putPort(imap,993);

success := CkImap_Connect(imap,'imap.example.com');
if (success = False) then
  begin
    Memo1.Lines.Add(CkImap__lastErrorText(imap));
    Exit;
  end;
success := CkImap_Login(imap,'user@example.com','myPassword');
if (success = False) then
  begin
    Memo1.Lines.Add(CkImap__lastErrorText(imap));
    Exit;
  end;

numMessages := CkImap_SelectMailbox(imap,'Inbox');
if (numMessages < 0) then
  begin
    Memo1.Lines.Add(CkImap__lastErrorText(imap));
    Exit;
  end;

//  Fetch messages 1..25 (or fewer if the mailbox is smaller).
count := 25;
if (count > numMessages) then
  begin
    count := numMessages;
  end;

failedSet := CkMessageSet_Create();
fetchedSet := CkMessageSet_Create();
bundle := CkEmailBundle_Create();
success := CkImap_FetchChunk2(imap,1,count,failedSet,fetchedSet,bundle);
if (success = False) then
  begin
    Memo1.Lines.Add(CkImap__lastErrorText(imap));
    Exit;
  end;

Memo1.Lines.Add('Fetched: ' + IntToStr(CkMessageSet_getCount(fetchedSet)));
Memo1.Lines.Add('Failed:  ' + IntToStr(CkMessageSet_getCount(failedSet)));

success := CkImap_Disconnect(imap);
if (success = False) then
  begin
    Memo1.Lines.Add(CkImap__lastErrorText(imap));
    Exit;
  end;

CkImap_Dispose(imap);
CkMessageSet_Dispose(failedSet);
CkMessageSet_Dispose(fetchedSet);
CkEmailBundle_Dispose(bundle);