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 2.0.0.16 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/