EagleFiler handles mail somewhat differently from the other file types. With Web pages, say, the idea is that you’re browsing in Safari or NetNewsWire, you come across something you want to save, and so you capture it into EagleFiler. You might put it in a folder or tag it to maintain some kind of organization. You might read the page at the time of capture, or you might read the Web archive in EagleFiler at some later date. So EagleFiler is letting you capture, organize, read, and archive the Web pages.
Mail is different because you probably have rules in your mail program to help organize your messages into different mailboxes, and you probably read your mail pretty much as it arrives. So for mail, EagleFiler acts as more of an archive.
Although you can always group messages in different ways using tags, and you can organize mailboxes however you want, messages don’t move between mailboxes. The idea is that the messages were already filed into their proper mailboxes in your mail client. By assuming this, EagleFiler is able to make some important optimizations to store your mail more efficiently and speed its browsing and searching. Although it’s possible, you probably don’t want to be bothered to import individual messages into EagleFiler every day. It’s easier to wait until you have some accumulation of mail that needs to be archived–a week or a month, depending on how much mail you receive.
The very first import is a little different, because it’s when I organize my mailboxes into folders in EagleFiler. The folder structure is somewhat different from that in my mail clients, since it’s geared towards how I will be browsing and searching the archived mail, rather than how I will be reading the incoming mail.
When I notice that my mailboxes are getting too large in Mailsmith or Mail, I import a bunch of them into EagleFiler and delete the original messages. Now, in EagleFiler, I have the older, organized mailboxes, and the newer ones, which are all at the top level. I want to get the mail from the newer mailboxes into the archive hierarchy. So I click on the Library source and sort by name. I find the pairs of old and new mailboxes with the same name and use the Merge Mailboxes command to combine them.
Result: the messages were moved from the mail client into the proper locations in the EagleFiler library.
There are lots of possible variations, of course. For example, if you get lots of mail in particular mailboxes, you might want to only merge up to a year’s worth of messages. That way you prevent an individual mailbox file from getting really large. And if you have a separate mailbox for each year, this makes it easy to search specific time periods–just select the years you want in the source list. I imagine that different people will find different techniques that work for them.