string sender = "my_account@gmail.com";
string recipient = "to@example.org";
string subject = "Test";
string body = "Hello World!";

// create SMTP client instance
using (var smtp = new Rebex.Net.Smtp())
{
    // connect to Gmail SMTP server
    smtp.Connect(gmail_smtp_hostname, SslMode.Explicit);

    // authenticate with your email address and password
    smtp.Login(sender, password);

    // send mail
    smtp.Send(sender, recipient, subject, body);

    // disconnect (not required, but polite)
    smtp.Disconnect();
}

// create IMAP client instance
using (var imap = new Rebex.Net.Imap())
{
    // connect to Gmail IMAP server
    imap.Connect("imap.gmail.com", SslMode.Implicit);

    // authenticate
    imap.Login(username, password);

    // select folder to work with
    imap.SelectFolder("INBOX");

    // get list of unread messages
    ImapMessageCollection list = imap.Search(ImapSearchParameter.Unread);

    // print some info
    foreach (ImapMessageInfo info in list)
    {
        Console.WriteLine("From: {0}", info.From);
        Console.WriteLine("To: {0}", info.To);
        Console.WriteLine("Subject: {0}", info.Subject);
    }

    // disconnect (not required, but polite)
    imap.Disconnect();
}

// create EWS client instance
using (var client = new Rebex.Net.Ews())
{
    // connect to Exchange server
    client.Connect(hostname, SslMode.Implicit);

    // authenticate
    client.Login(username, password);

    // to select folder to work with use either:
    // - client.FindFolder(EwsFolderId.Root, "folderName")
    // - predefined folder id
    var folder = EwsFolderId.Inbox;

    // get list of unread messages
    var list = client.Search(
        folder,
        EwsSearchParameter.IsRead(false));

    // print some info
    foreach (EwsMessageInfo messageInfo in list)
    {
        Console.WriteLine("From: {0}", messageInfo.From);
        Console.WriteLine("To: {0}", messageInfo.To);
        Console.WriteLine("Subject: {0}", messageInfo.Subject);
    }

    // disconnect (not required, but polite)
    client.Disconnect();
}

// create Graph client instance
using (var client = new Rebex.Net.GraphClient())
{
    // connect to Exchange Online (Microsoft 365) server
    client.Connect();

    // authenticate with your OAuth access token
    client.Login(token);

    // get first page of a list of unread messages from the 'Inbox' folder
    var unread = GraphMessageSearchParameter.IsRead(false);
    GraphMessageCollection messages = client.Search(GraphFolderId.Inbox, unread);

    // print some info
    foreach (GraphMessageInfo info in messages)
    {
        Console.WriteLine("Subject: {0}", info.Subject);
        Console.WriteLine("From: {0}", info.From);
        Console.WriteLine("To: {0}", info.To);
    }

    // disconnect (not required, but polite)
    client.Disconnect();
}

// create POP3 client instance
using (var pop3 = new Rebex.Net.Pop3())
{
    // connect to Gmail POP3 server
    pop3.Connect("pop.gmail.com", SslMode.Implicit);

    // authenticate
    pop3.Login(username, password);

    // get message list
    Pop3MessageCollection list = pop3.GetMessageList();

    // print some info
    Console.WriteLine("{0} email(s) found.", list.Count);

    // download all messages
    foreach (Pop3MessageInfo info in list)
    {
        MailMessage mail = pop3.GetMailMessage(info.SequenceNumber);

        // do something with the mail
        // ...
    }

    // disconnect (required to commit delete operations)
    pop3.Disconnect();
}

// create an instance of MsgMessage
var message = new MsgMessage();

// load a message from file
message.Load(@"C:\MyData\sample.msg");

// .. work with the message

// save the message into a memory stream for later use
var stream = new MemoryStream();
message.Save(stream);
stream.Position = 0;