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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    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 := chilkat.NewImap()

    imap.SetSsl(true)
    imap.SetPort(993)

    success = imap.Connect("imap.example.com")
    if success == false {
        fmt.Println(imap.LastErrorText())
        imap.DisposeImap()
        return
    }

    success = imap.Login("user@example.com","myPassword")
    if success == false {
        fmt.Println(imap.LastErrorText())
        imap.DisposeImap()
        return
    }

    numMessages := imap.SelectMailbox("Inbox")
    if numMessages < 0 {
        fmt.Println(imap.LastErrorText())
        imap.DisposeImap()
        return
    }

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

    failedSet := chilkat.NewMessageSet()
    fetchedSet := chilkat.NewMessageSet()
    bundle := chilkat.NewEmailBundle()
    success = imap.FetchChunk2(1,count,failedSet,fetchedSet,bundle)
    if success == false {
        fmt.Println(imap.LastErrorText())
        imap.DisposeImap()
        failedSet.DisposeMessageSet()
        fetchedSet.DisposeMessageSet()
        bundle.DisposeEmailBundle()
        return
    }

    fmt.Println("Fetched: ", fetchedSet.Count())
    fmt.Println("Failed:  ", failedSet.Count())

    success = imap.Disconnect()
    if success == false {
        fmt.Println(imap.LastErrorText())
        imap.DisposeImap()
        failedSet.DisposeMessageSet()
        fetchedSet.DisposeMessageSet()
        bundle.DisposeEmailBundle()
        return
    }


    imap.DisposeImap()
    failedSet.DisposeMessageSet()
    fetchedSet.DisposeMessageSet()
    bundle.DisposeEmailBundle()