If you need full access to your email supporting IMAP from .NET here is a very good open-source library called ImapX.
ImapX is a cross-platform IMAP library for .NET supporting .Net 2.0 - 4.5, Mono and Windows Phone.
Current stable version is ImapX 22.214.171.124 released on May 1, 2014.
I give it 5 stars because ImapX just works with my C# deployment. It supports attachements which makes it superior to Atom Inbox feed, easy to implement and well documented.
You can read the documentation here https://imapx.codeplex.com/