(Lianja) 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.

Note: This example requires Chilkat v11.0.0 or greater.

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llSuccess = .F.

// 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.
loMailman = createobject("CkMailMan")

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

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

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

loSbXml = createobject("CkStringBuilder")
loHtSeenUidls = createobject("CkHashtable")
loFac = createobject("CkFileAccess")
if (loFac.FileExists(lcSeenUidlsPath) = .T.) then
    llSuccess = loSbXml.LoadFile(lcSeenUidlsPath,"utf-8")
    if (llSuccess = .F.) then
        ? loSbXml.LastErrorText
        release loMailman
        release loSbXml
        release loHtSeenUidls
        release loFac
        return
    endif

    loHtSeenUidls.AddFromXmlSb(loSbXml)
endif

// Get the complete list of UIDLs on the mail server.
loStUidls = createobject("CkStringTable")
llSuccess = loMailman.FetchUidls(loStUidls)
if (llSuccess = .F.) then
    ? loMailman.LastErrorText
    release loMailman
    release loSbXml
    release loHtSeenUidls
    release loFac
    release loStUidls
    return
endif

// Build a list of unseen UIDLs
loStUnseenUidls = createobject("CkStringTable")

i = 0
lnCount = loStUidls.Count
do while i < lnCount
    lcUidl = loStUidls.StringAt(i)
    if (loHtSeenUidls.Contains(lcUidl) <> .T.) then
        loStUnseenUidls.Append(lcUidl)
    endif

    i = i + 1
enddo

if (loStUnseenUidls.Count = 0) then
    ? "No unseen emails!"
    release loMailman
    release loSbXml
    release loHtSeenUidls
    release loFac
    release loStUidls
    release loStUnseenUidls
    return
endif

// Download the unseen emails, adding each UIDL to the "seen" hash table.
loEmail = createobject("CkEmail")

lnCount = loStUnseenUidls.Count
i = 0
do while i < lnCount
    // Download the full email.
    lcUidl = loStUnseenUidls.StringAt(i)
    llSuccess = loMailman.FetchByUidl(lcUidl,.F.,0,loEmail)
    if (llSuccess = .F.) then
        ? loMailman.LastErrorText
        release loMailman
        release loSbXml
        release loHtSeenUidls
        release loFac
        release loStUidls
        release loStUnseenUidls
        release loEmail
        return
    endif

    ? str(i)
    ? "From: " + loEmail.From
    ? "Subject: " + loEmail.Subject

    // Add this UIDL to the "seen" hash table.
    loHtSeenUidls.AddStr(lcUidl,"")

    i = i + 1
enddo

loMailman.Pop3EndSession()

// Update the "seen" UIDLs file.
loSbXml.Clear()
loHtSeenUidls.ToXmlSb(loSbXml)
llSuccess = loSbXml.WriteFile(lcSeenUidlsPath,"utf-8",.F.)
if (llSuccess = .F.) then
    ? loSbXml.LastErrorText
    release loMailman
    release loSbXml
    release loHtSeenUidls
    release loFac
    release loStUidls
    release loStUnseenUidls
    release loEmail
    return
endif

? "Success."


release loMailman
release loSbXml
release loHtSeenUidls
release loFac
release loStUidls
release loStUnseenUidls
release loEmail