(Node.js) How to Download Messages in MessageSet One at a Time

If a message set contains a huge number of emails, it's NOT a good idea to try to download all at once into an email bundle using a method such as FetchBundle. It's better to iterate over the messages in the set to download one by one.

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

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOS

var os = require('os');
if (os.platform() == 'win32') {  
  var chilkat = require('@chilkat/ck-node23-win64'); 
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node23-linux-arm');
    } else if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node23-linux-arm64');
    } else {
        var chilkat = require('@chilkat/ck-node23-linux-x64');
    }
} else if (os.platform() == 'darwin') {
  var chilkat = require('@chilkat/ck-node23-mac-universal');
}

function chilkatExample() {

    var success = false;

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

    var imap = new chilkat.Imap();

    // Connect using TLS.
    imap.Ssl = true;
    imap.Port = 993;
    success = imap.Connect("imap.example.com");
    if (success == false) {
        console.log(imap.LastErrorText);
        return;
    }

    // Authenticate
    success = imap.Login("email_account_login","email_account_password");
    if (success == false) {
        console.log(imap.LastErrorText);
        return;
    }

    // Select an IMAP mailbox
    success = imap.SelectMailbox("Inbox");
    if (success == false) {
        console.log(imap.LastErrorText);
        return;
    }

    // Search for messages and return a set of matching messages.
    // (This example will simply search for ALL messages.)
    var fetchUids = true;

    var messageSet = new chilkat.MessageSet();
    success = imap.QueryMbx("ALL",fetchUids,messageSet);
    if (success == false) {
        console.log(imap.LastErrorText);
        return;
    }

    console.log("Number of messages = " + messageSet.Count);

    var email = new chilkat.Email();
    var i = 0;
    while (i < messageSet.Count) {
        success = imap.FetchEmail(false,messageSet.GetId(i),fetchUids,email);
        if (success == false) {
            console.log(imap.LastErrorText);
            return;
        }

        console.log(email.From + "; " + email.Subject);

        i = i+1;
    }

    console.log("OK");

}

chilkatExample();