In Microsoft Outlook/Exchange you have the option of saving messages outside of Outlook into your files system with your other documents (Word Documents, Spreadsheets, etc). You can then open up the documents and they open in Outlook/Exchange.
I would like Lotus Notes to be able to do the same thing. Export E-mail messages to your file system and then open them and the will open up in Lotus Notes. You can choose to save messages as text files or Word documents but they you can't reply to the messages or do any other E-mail type stuff.
I have a couple of Sales people and the President of the company would like this. Their reasoning is that they would then have all their information related to a customer or project in one system file folder. They don't need to create a seperate folder in your E-mail. This would also help with mail quotas. Anyone who wants to save their E-mails can get them out of Notes. The only downside is if the person does not backup their messages to a network device they could be lost if the hard drive dies.
I would think that this would be very simlar to the way the iCalendar entries are made. We can send meetings outside of Notes and have other mail systems recognize them.
Updated: 5/22/08: After reading some of the posts I thought I would add some more ideas. If possible, give the user the option to encrypt the message with the Notes.id so that only the user who exports the message can read it. Using a mail archive sort of solves the problem but it does not let you file your e-mail in your computer's file system with all the other related documents. I agree with the loss of security and control of the messages once they leave the Notes databases. If this were to be done I like the idea of using a common file format that can possilbly be read by by Notes or other E-mail programs and can be replied to would be ideal.
Updated 5/30/08: I agree with the fact that OpenNTF will allow you to export e-mail using the More - Forward MIME to RFC-822 option. That would be cool to have in the standard template, but it would also be cool to have the Notes client read the exported EML file instead of Outlook trying to open the file. That way if we get documents saved by other clients (Outlook) we could read them in Notes instead of having to have them open in Outlook. We would also be able to reply or forward the messages at a later time.