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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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llSuccess = .F.

//  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.

loImap = createobject("CkImap")

loImap.Ssl = .T.
loImap.Port = 993

llSuccess = loImap.Connect("imap.example.com")
if (llSuccess = .F.) then
    ? loImap.LastErrorText
    release loImap
    return
endif

llSuccess = loImap.Login("user@example.com","myPassword")
if (llSuccess = .F.) then
    ? loImap.LastErrorText
    release loImap
    return
endif

lnNumMessages = loImap.SelectMailbox("Inbox")
if (lnNumMessages < 0) then
    ? loImap.LastErrorText
    release loImap
    return
endif

//  Fetch messages 1..25 (or fewer if the mailbox is smaller).
lnCount = 25
if (lnCount > lnNumMessages) then
    lnCount = lnNumMessages
endif

loFailedSet = createobject("CkMessageSet")
loFetchedSet = createobject("CkMessageSet")
loBundle = createobject("CkEmailBundle")
llSuccess = loImap.FetchChunk2(1,lnCount,loFailedSet,loFetchedSet,loBundle)
if (llSuccess = .F.) then
    ? loImap.LastErrorText
    release loImap
    release loFailedSet
    release loFetchedSet
    release loBundle
    return
endif

? "Fetched: " + str(loFetchedSet.Count)
? "Failed:  " + str(loFailedSet.Count)

llSuccess = loImap.Disconnect()
if (llSuccess = .F.) then
    ? loImap.LastErrorText
    release loImap
    release loFailedSet
    release loFetchedSet
    release loBundle
    return
endif



release loImap
release loFailedSet
release loFetchedSet
release loBundle