We use Colligo Contributor for this.  Users can drag and drop entire e-mails or just attachments into Sharepoint document libraries using the Outlook folder tree.

Two nice things about Colligo are (1) it has the ability to extract e-mail fields (from, to, sent date, receive date, subject) into Sharepoint metadata fields and (2) when you drop an e-mail or attachment into the Colligo-linked library, it will pop up a window and ask you for the Content Type and any Sharepoint metadata fields required on the library.

If you are looking to automatically integrate emails into you SharePoint portal solutions you should check out our new web part which we are looking for test installations for.

Our product is called Email-Manager(tm) and it enables you to integrate emails in your portal in a matter of minutes. Emails (send and received) on the exchange server are automatically captured and store in a SQL database. Via our ready made web part (you can also use our SDK and access our web services directly) you are then able to incorporate the emails into you team site (including attachments etc.)

We also give away the source code for you to do even further development and customization to the product.

The product is in beta right now, but is already installed in many live environments - we are looking for more test installations, so if you are interested please let us know.

Check it out on www.oppsol.com and there is a recorded demo here: emmdownload.com/sharepoint

Kind regards

Kenneth