(C#) Reading Unread POP3 Email

The POP3 protocol does not provide the ability to ask the server which emails are "unread". Furthermore, a pure POP3 server does not even keep this information. Some servers, such as Exchange Server, expose both POP3 and IMAP interfaces. In these cases, information about read/unread status exists on the server, but it is only available via the IMAP protocol. Email clients such as Outlook and Thunderbird keep read/unread information on the client computer. This example demonstrates how UIDLs can be saved to track and read "unread" email.

Chilkat .NET Downloads Chilkat .NET Framework Chilkat for .NET Core

// 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.
Chilkat.MailMan mailman = new Chilkat.MailMan();

// Set the POP3 server's hostname
mailman.MailHost = "pop.someMailServer.com";

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

// You may keep a list of already-seen UIDLs in a text file:
// If this is the first time you're running this example,
// create an empty text file named "seenUidls.txt"
Chilkat.StringArray saSeenUidls = new Chilkat.StringArray();
bool success = saSeenUidls.LoadFromFile("seenUidls.txt");
if (success != true) {
    Debug.WriteLine("failed to load seenUidls.txt");
    return;
}

// Get the complete list of UIDLs on the mail server.
Chilkat.StringArray saUidls = mailman.GetUidls();
if (mailman.LastMethodSuccess == false) {
    Debug.WriteLine(mailman.LastErrorText);
    return;
}

// Create a new string array object (it's an object, not an actual array)
// and add the UIDLs from saUidls that aren't already seen.
Chilkat.StringArray saUnseenUidls = new Chilkat.StringArray();

int i = 0;
int n = saUidls.Count;
while (i < n) {
    if (saSeenUidls.Contains(saUidls.GetString(i)) != true) {
        success = saUnseenUidls.Append(saUidls.GetString(i));
    }

    i = i + 1;
}

if (saUnseenUidls.Count == 0) {
    Debug.WriteLine("No unseen emails!");

    return;
}

// Download in full the unseen emails:
Chilkat.EmailBundle bundle = mailman.FetchMultiple(saUnseenUidls);
if (mailman.LastMethodSuccess == false) {
    Debug.WriteLine(mailman.LastErrorText);

    return;
}

Chilkat.Email email = null;
i = 0;
while (i < bundle.MessageCount) {
    email = bundle.GetEmail(i);
    Debug.WriteLine(email.From);
    Debug.WriteLine(email.Subject);
    Debug.WriteLine("----");

    i = i + 1;
}

// Save saUidls to "seenUidls.txt"
success = saUidls.SaveToFile("seenUidls.txt");