VB.NET

Fetch a Range of IMAP Messages by Sequence Number

Demonstrates the Chilkat Imap.FetchRange method, which downloads a contiguous run of messages by sequence number. The arguments are headersOnly, the starting sequence number, the count of messages, and the EmailBundle that receives them. This example uses the message count returned by SelectMailbox to fetch the headers of the 10 most recent messages.

Background: IMAP sequence numbers are 1-based positions within the selected mailbox, from 1 (oldest) to the message count (newest), and they shift whenever messages are expunged. That makes FetchRange ideal for "give me the newest N" style paging within a single session, but note that sequence numbers are not stable identifiers across sessions the way UIDs are — use a UID-based approach if you need to remember which messages you have already seen.

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Dim success As Boolean = False

'  Demonstrates the Imap.FetchRange method, which downloads a contiguous run of messages by
'  sequence number.  The 1st argument is headersOnly, the 2nd is the starting sequence number,
'  the 3rd is the count of messages, and the 4th is the EmailBundle that receives them.

Dim imap As New Chilkat.Imap

imap.Ssl = True
imap.Port = 993

success = imap.Connect("imap.example.com")
If (success = False) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If

success = imap.Login("user@example.com","myPassword")
If (success = False) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If


'  SelectMailbox returns the number of messages in the mailbox, or -1 on failure.
Dim numMessages As Integer = imap.SelectMailbox("Inbox")
If (numMessages < 0) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If


'  Download the 10 most recent messages (headers only).
Dim startSeqnum As Integer = numMessages - 9
If (startSeqnum < 1) Then
    startSeqnum = 1
End If


Dim bundle As New Chilkat.EmailBundle
success = imap.FetchRange(True,startSeqnum,10,bundle)
If (success = False) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If


Dim n As Integer = bundle.MessageCount
Debug.WriteLine("Fetched " & n & " message headers.")

success = imap.Disconnect()
If (success = False) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If