VB.NET

Fetch an IMAP Attachment into a BinData

Demonstrates the Chilkat Imap.FetchAttachmentBd method, which stores one attachment's bytes in a BinData object. The first argument is the Email, the second is the zero-based attachment index, and the third is the BinData, which is cleared before the operation. This example fetches the first attachment and prints its byte count.

Background: A BinData holds raw bytes, so it works for any attachment type — image, PDF, zip, and so on. From there you can save it, hash it, or hand it to another API expecting a byte buffer, all without touching the filesystem. Use the string/StringBuilder variants only when the attachment is known to be text.

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Dim success As Boolean = False

'  Demonstrates the Imap.FetchAttachmentBd method, which downloads one attachment's bytes into
'  a BinData object.  The 1st argument is the Email, the 2nd is the zero-based attachment
'  index, and the 3rd is the BinData (which is cleared first).
'  
'  The message is fetched headers-only, then the attachment is downloaded on demand.

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


success = imap.SelectMailbox("Inbox")
If (success = False) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If


'  Fetch only the message headers.  Attachment bodies are NOT downloaded, but the ckx-imap-*
'  metadata describing the attachments is present, so the attachment info methods still work.
Dim headersOnly As Boolean = True
Dim useUid As Boolean = False
Dim seqNum As Integer = 1
Dim email As New Chilkat.Email
success = imap.FetchEmail(headersOnly,seqNum,useUid,email)
If (success = False) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If


Dim numAttach As Integer = imap.GetMailNumAttach(email)
If (numAttach > 0) Then
    '  Download just the first attachment's bytes from the server into a BinData.
    Dim bd As New Chilkat.BinData
    success = imap.FetchAttachmentBd(email,0,bd)
    If (success = False) Then
        Debug.WriteLine(imap.LastErrorText)
        Exit Sub
    End If

    Debug.WriteLine("Attachment size: " & bd.NumBytes & " bytes")
End If


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