Advanced MIME Parser/Creator/Editor de LumiSoft :
http://www.codeproject.com/KB/cs/mime_project.aspx
C’est la partie LumiSoft.Net.Mime de sa librairie, qui est grosse …
http://www.lumisoft.ee/lswww/download/downloads/Net/LumiSoft.Net.zip

C#Mail is a library to send or receive mail written by C#.
http://csharpmail.codeplex.com/
Documentation : http://www.higlabo.com/Mail/Pop3/index.html
Sous licence GNU GPL

Un parser plus simple qui passe d’un fichier EML vers un Microsoft .Net MailMessage
http://www.codeproject.com/KB/office/EML_ReaderEx.aspx

POP3 Email Client (.NET 2.0) : C# class making it easy to interact with POP3 email server, like listing of emails, download and deletion. Special attention was given to reliable connection control. The code was tested for several months with Google Gmail, including SSL.
http://www.codeproject.com/KB/IP/Pop3MailClient.aspx
POP3 Email Client with full MIME Support
http://www.codeproject.com/KB/IP/Pop3MimeClient.aspx

Sinon classiquement http://www.opennetcf.com/Default.aspx?tabid=65
A surtout un client SMTP : http://www.opennetcf.com/library/sdf/html/509f7196-ae6e-354f-4a7d-e563ef86416b.htm
http://blog.opennetcf.com/ncowburn/2008/11/26/ANNSmartDeviceFramework23.aspx

Encore un : http://anmar.eu.org/projects/sharpmimetools/
Utilise ici, avec exemple simple de POP3 : http://ifdefined.com/bugtrackernet.html

Tuto sur la manière de rendre un controle éditable :
http://blogs.msdn.com/b/bluecollar/archive/2007/02/08/adding-compact-framework-design-time-attributes-or-more-fun-with-textboxes.aspx