12 Aug 2008

Apple Mail Causing 'Rendering Errors' on Outlook 2007

A few months ago, without giving it a whole lot of thought, I set up my home computers to retrieve my work email, by adding my work account to Apple Mail. This is, as any Apple Mail user can attest, pretty trivial to do. Even the relatively old version of Mail that I use, version 2.1.3 (753.1/753), has built-in support for Exchange servers, and is known to work reasonably well with the beast from Redmond. All you need to do is enter your Exchange server (“Incoming mail server” in Mail), Outlook Web Access server, and SMTP server information, and Mail does the rest.

How exactly Mail deals with Exchange servers is still a bit of a mystery to me; I think it stops short of emulating the Exchange protocol completely, but instead uses a combination of IMAP and HTTP connections; IMAP for some functions (mailbox and personal folders) and WebDAV into the OWA server for others (public folders).

I didn’t give it a whole lot of thought because it ‘just worked’ as soon as I put in the correct server information. My work email started showing up in my Mail inbox, and I considered the project finished. No trouble at all.

At least, no trouble on my end. Several weeks passed, and all the while my Macs were happily connecting to the hosted Exchange service that runs my work’s email (which shall, for the moment anyway, remain nameless), downloading messages and attachments. I even got S/MIME to work without issues. But then, out of the blue, I got an email from the operations department of the email-hosting service, asking me to give them a call right away.

When I called, I learned that something I was doing was causing thousands of “rendering errors” to pop up in their server logs. Initially they thought this was due to a corrupt message, but after checking all my messages (a tedious process), I mentioned that I was using Mail to connect. When I disabled Apple Mail, the errors stopped flowing. When I turned it back on, they restarted.

This, of course, went over pretty much like a fart in church. Since they don’t officially support anything but Outlook on Windows, if the problem couldn’t be resolved, I’d just have to stop using Mail. (Sadly the alternative – get another hosting provider – isn’t really an option.)

So far, I’ve yet to find a solution. It’s made difficult by the fact that the errors don’t seem to affect me on this end – as far as I can tell, Apple Mail works perfectly. But whatever it’s doing on the far end seems to really displease the hosting service’s sysops.

Googling hasn’t turned up anyone else having the same problem, either. This strikes me as odd – given that Apple Mail has a distinct option for connecting to an Exchange server, I doubt I’m the only person to try and use it. Furthermore, the problem seems to be specific to the desktop version of Mail; other people I know who get their email via the iPhone haven’t gotten any nastygrams, so it’s not an all-IMAP or even all-Apple issue. Yet it seems to happen with both of my Macs (both running 10.4 and Mail.app 2.1.3), regardless of whether they’re configured to connect to the hosting service via Exchange or IMAP, and whether they connect from home or some other location.

If anyone has ever experienced this problem, I’d be eager to hear any reports of possible solutions, or even just descriptions of what was happening. (Details on the errors from the server side in particular would be welcome, since the hosting company hasn’t been all that forthcoming with what’s going on.) Given the MS-centricity of the hosting provider, I think that finding my own solution to the issue is going to be the only way to continue using Mail.

The only potential solution I’ve come up with so far is to run a MUA/MTA on my home server (Ubuntu Linux), and have it fetch messages from the hosting provider via IMAP every few minutes, spool them, and then make them available to my Macs using UW-IMAPD or Courier IMAP. This strikes me as a nasty kludge and a possible source of significant delay in receiving messages, but it would at least create a Linux “buffer” between Apple Mail and Exchange. If they can’t be made to play nice with each other, this may be the only way to keep everyone happy.

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