B4X Requires Chilkat v11.0.0+

Reading Unread POP3 Email

The POP3 protocol cannot determine which emails are "unread," and pure POP3 servers do not store this information. Servers like Exchange Server, offering both POP3 and IMAP interfaces, do contain read/unread data, but it's only accessible through IMAP. Email clients like Outlook and Thunderbird store read/unread statuses on the client side. The example demonstrates using UIDLs to track and manage "unread" emails. B4X

Dim success As Boolean = False

'  This example requires the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

'  The mailman object is used for receiving (POP3) 
'  and sending (SMTP) email.
Dim mailman As ChilkatMailMan
mailman.Initialize("mailman")

'  Set the POP3 server's hostname
mailman.MailHost = "pop.example.com"

'  Set the POP3 login/password.
mailman.PopUsername = "***"
mailman.PopPassword = "***"

'  Keep a records of already-seen UIDLs in hash table serialized to an XML file.
Dim seenUidlsPath As String = "c:/temp/seenUidls.xml"

Dim sbXml As ChilkatStringBuilder
sbXml.Initialize
Dim htSeenUidls As ChilkatHashtable
htSeenUidls.Initialize
Dim fac As ChilkatFileAccess
fac.Initialize
If fac.FileExists(seenUidlsPath) = True Then
    success = sbXml.LoadFile(seenUidlsPath, "utf-8")
    If success = False Then
        Log(sbXml.LastErrorText)
        Return
    End If

    htSeenUidls.AddFromXmlSb(sbXml)
End If


'  Get the complete list of UIDLs on the mail server.
Dim stUidls As ChilkatStringTable
stUidls.Initialize
success = mailman.FetchUidls(stUidls)
If success = False Then
    Log(mailman.LastErrorText)
    Return
End If


'  Build a list of unseen UIDLs
Dim stUnseenUidls As ChilkatStringTable
stUnseenUidls.Initialize

Dim uidl As String
Dim i As Int = 0
Dim count As Int = stUidls.Count
Do While i < count
    uidl = stUidls.StringAt(i)
    If htSeenUidls.Contains(uidl) <> True Then
        stUnseenUidls.Append(uidl)
    End If

    i = i + 1
Loop

If stUnseenUidls.Count = 0 Then
    Log("No unseen emails!")
    Return
End If


'  Download the unseen emails, adding each UIDL to the "seen" hash table.
Dim email As ChilkatEmail
email.Initialize

count = stUnseenUidls.Count
i = 0
Do While i < count
    '  Download the full email.
    uidl = stUnseenUidls.StringAt(i)
    success = mailman.FetchByUidl(uidl, False, 0, email)
    If success = False Then
        Log(mailman.LastErrorText)
        Return
    End If


    Log(i)
    Log("From: " & email.From)
    Log("Subject: " & email.Subject)

    '  Add this UIDL to the "seen" hash table.
    htSeenUidls.AddStr(uidl, "")

    i = i + 1
Loop

mailman.Pop3EndSession

'  Update the "seen" UIDLs file.
sbXml.Clear
htSeenUidls.ToXmlSb(sbXml)
success = sbXml.WriteFile(seenUidlsPath, "utf-8", False)
If success = False Then
    Log(sbXml.LastErrorText)
    Return
End If


Log("Success.")