using c# .net libraries to check for IMAP messages from gmail servers

I'd recommend looking at MailKit as it is probably the most robust mail library out there and it's Open Source (MIT).

One of the awesome things about MailKit is that all network APIs are cancelable (something I haven't seen available in any other IMAP library).

It's also the only library that I know of that supports threading of messages.

using System;
using System.Net;
using System.Threading;

using MailKit.Net.Imap;
using MailKit.Search;
using MailKit;
using MimeKit;

namespace TestClient {
    class Program
    {
        public static void Main (string[] args)
        {
            using (var client = new ImapClient ()) {
                using (var cancel = new CancellationTokenSource ()) {
                    client.Connect ("imap.gmail.com", 993, true, cancel.Token);

                    // If you want to disable an authentication mechanism,
                    // you can do so by removing the mechanism like this:
                    client.AuthenticationMechanisms.Remove ("XOAUTH");

                    client.Authenticate ("joey", "password", cancel.Token);

                    // The Inbox folder is always available...
                    var inbox = client.Inbox;
                    inbox.Open (FolderAccess.ReadOnly, cancel.Token);

                    Console.WriteLine ("Total messages: {0}", inbox.Count);
                    Console.WriteLine ("Recent messages: {0}", inbox.Recent);

                    // download each message based on the message index
                    for (int i = 0; i < inbox.Count; i++) {
                        var message = inbox.GetMessage (i, cancel.Token);
                        Console.WriteLine ("Subject: {0}", message.Subject);
                    }

                    // let's try searching for some messages...
                    var query = SearchQuery.DeliveredAfter (DateTime.Parse ("2013-01-12"))
                        .And (SearchQuery.SubjectContains ("MailKit"))
                        .And (SearchQuery.Seen);

                    foreach (var uid in inbox.Search (query, cancel.Token)) {
                        var message = inbox.GetMessage (uid, cancel.Token);
                        Console.WriteLine ("[match] {0}: {1}", uid, message.Subject);
                    }

                    client.Disconnect (true, cancel.Token);
                }
            }
        }
    }
}

The URL listed here might be of interest to you

http://www.codeplex.com/InterIMAP

which was extension to

http://www.codeproject.com/KB/IP/imaplibrary.aspx?fid=91819&df=90&mpp=25&noise=5&sort=Position&view=Quick&fr=26&select=2562067#xx2562067xx

As the author of the above project i can say that yes it does support SSL.

I am currently working on a new version of the library that will be completely asynchronous to increase the speed with which it can interact with IMAP servers.

That code, while not complete, can be downloaded, along with the original synchronous library (which also supports SSL), from the code plex site linked to above.