DotNetOpenMail - an SMTP client library for .net, written in C#.
Create basic text and html emails with attachments that can be sent
via an SMTP server.
Please visit http://dotnetopenmail.sourceforge.net/ for some examples.
InboxVault is a service built on top of Documentum 6, using DFS, and hMailServer, an open-source .NET-based email server. The idea of InboxVault is to create a service that makes getting to your content as easy as sending an e-mail.