Fetch a Chunk of Messages, Tracking Failures

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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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bool 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.

Chilkat.Imap imap = new Chilkat.Imap();

imap.Ssl = true;
imap.Port = 993;

success = imap.Connect("imap.example.com");
if (success == false) {
    Debug.WriteLine(imap.LastErrorText);
    return;
}

success = imap.Login("user@example.com","myPassword");
if (success == false) {
    Debug.WriteLine(imap.LastErrorText);
    return;
}

int numMessages = imap.SelectMailbox("Inbox");
if (numMessages < 0) {
    Debug.WriteLine(imap.LastErrorText);
    return;
}

//  Fetch messages 1..25 (or fewer if the mailbox is smaller).
int count = 25;
if (count > numMessages) {
    count = numMessages;
}

Chilkat.MessageSet failedSet = new Chilkat.MessageSet();
Chilkat.MessageSet fetchedSet = new Chilkat.MessageSet();
Chilkat.EmailBundle bundle = new Chilkat.EmailBundle();
success = imap.FetchChunk2(1,count,failedSet,fetchedSet,bundle);
if (success == false) {
    Debug.WriteLine(imap.LastErrorText);
    return;
}

Debug.WriteLine("Fetched: " + Convert.ToString(fetchedSet.Count));
Debug.WriteLine("Failed:  " + Convert.ToString(failedSet.Count));

success = imap.Disconnect();
if (success == false) {
    Debug.WriteLine(imap.LastErrorText);
    return;
}