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Field NotesIMAP Saves the World

R'ykandar Korra'ti

Sometimes solutions to new, small problems can solve old, large problems as well. This is one of those cases.

Last winter, our Web administrator bought a MacBook. She had been running Windows® exclusively, but now she'd have both OS X and, in a virtual machine, Windows XP for syncing her Windows Mobile® devices and a few other small tasks.

She needed access to all her mail archives from both operating systems. But she didn't want to run Entourage on the Mac side—that would have been too easy. No, she wanted to run, the e-mail client included with OS X. Incidentally, she'd kept everything in her laptop's local store, unmirrored. My job: make this go.

Having archives be readable everywhere presented only the small problem mentioned previously because—and this is the first moral of our story—everything, including Exchange Server, Microsoft® Office Outlook®, and Mail, speaks IMAP4. IMAP4 is a messaging protocol for handling on-server message stores from thin clients. It has fewer features than Exchange users might enjoy, but it works (see How IT Works: IMAP4 in the March-April 2006 issue of TechNet Magazine at

So, change a few settings to bring IMAP4 over SSL online, copy all of her local folders up onto the server, and ping! She could access mail on all clients and keep her Windows Mobile devices updated. Problem solved.

But coming up with a simple solution to a potentially hairy problem is like getting a new table saw. Suddenly you start looking for more plywood, and before you know it, you've got stage sets built and you're ready to play "Romeo and Juliet."

Our tiny ISP runs Windows, OS X, Mac OS, Linux, and even has one lonely old AmigaOS system hanging around on the fringes looking for a friend. Long ago, we hosted Usenet news and UUCP mail on that Amiga. It created archives stored away in RFC-733/Amiga­UUCP format. We also have Microsoft Mail archives (.mmf format) and some similar-vintage UNIX mail archives (.mbox format). They've all just been sitting there, mocking us—a problem we'd consider every so often and then flee, screaming.

This scenario brings us to the second moral of our story, the Danger Hacker motto of lore: Never Erase What You Can't Replace.

We tackled the Microsoft Mail archives first. Outlook hasn't been able to import .mmf files in some time. But as we've upgraded clients over the years, we've kept at least one license of each older product because you just never know. As a result, our license rack forms a timeline of the Microsoft Corporation. Need MS-DOS®? OS/2 1.31? Microsoft Mail? Office 95? Sure! Would you like that in English or in French?

Outlook 2000 imported .mmf, but its IMAP support was strange and occasionally dropped header data. Also, it couldn't talk to IMAP4 and Exchange servers at the same time. This was vexing, but not a showstopper. Import the .mmf files via Outlook 2000, upgrade to our retained license of Outlook 2003, and a few hours of drag and drop later: 15-year-old archives online and viewable anywhere. Similarly for .mbox, throw an mbox-compatible IMAP server onto a Linux machine and put the .mbox-format archives in its working directory. Then use the Outlook IMAP support to connect and copy folders over to the production server of choice.

The Amiga archives, on the other hand, required writing a small bundle of C code to convert the RFC-733 headers into RFC-822 format, ditch the old SysV-style message dividers, and retrieve the strange From: line data from the special hell in which it lived. This is the price for letting problems sit too long. But once done, Amiga­UUCP format became .mbox format. And thrown into the same working directory, the Outlook IMAP4 brought the mail right down, good as new. It even packaged up the attachments very nicely for us.

We now have archives back to 1990 online in one unified format, and we're looking around for more archives ... just because we can. Is that healthy?

R'ykandar Korra'ti, postmaster for a small co-op ISP, lives near Seattle with her partner, Anna. Having previously shipped mail products at Microsoft, she's writing technical articles when not working on deeply obscure mandolin song lyrics. Booking agents can reach her at

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