Insight: Outlook, Telescopes and Microscopes, by Mark Thurston.

There is a fairly narrow band of Managed Services incidents that could genuinely be described as "edutaining". At one end of the spectrum, there's the printer that has decided to eat 3 reams of paper for lunch before dropping off for a well-deserved post-prandial afternoon’s snooze. At the other end, there’s the real stinker that goes on for weeks of network and Fiddler traces, such as the one we had regarding Kerberos authentication against Azure Storage Accounts when accessed via Private Link. (The latter being one where we eventually ended up talking to the 3rd line team in Seattle who apologised that the documentation had a small, subtle but significant error in it. They kindly sent us the brand new corrected version – problem solved.)

In the middle, there are the rare ones that one initially thinks “oh, you’ve probably just clicked the wrong thing”, or “oh, it’s probably just your AV solution being a little overzealous”. Over time, you realise that the problem is not so trivial and truly weird.

Well, one of our eagle-eyed MSP customers (and by “eagle-eyed” I’m thinking of a Bald Eagle with a James Webb Telescope attached to each eye) spotted an issue with the Preview Pane in Outlook being slow to load the message. What makes this particular incident “eagle-eyed” is that they noticed that the problem only surfaced when previewing messages following an Outlook search! (So, already off the beaten track.) It was at that point that we got involved.

Naturally, we did the usual diagnostic things, After each experiment, we exclaimed, with ever greater surprise “well, that really is weird!”. So, we donned our cryogenic transmission electron microscopes and dived right in…

We noticed that if you search for a person without the email domain (fred.bloggs), the problem goes away, but searching their fully SMTP address (fred.bloggs@acme.com) surfaces the problem. Weird indeed!

To cut a long story short, it transpired that the problem is the Outlook option to highlight the searched text in the preview pane following a search. If the search term includes an “@”, it hangs for a few seconds before loading the message. The bodge solution is to disable the option in Outlook. (File, Options, Search, Switch off “Highlight search terms in the results”.)

The point of this missive isn’t so much about the fix, but the fact that at the end of it, we though “someone must surely have noticed this before?”. We Googled (and “Binged”, of course), but found nothing. It may be that we didn’t search hard enough, but it is possible that, between all the James Webb Telescopes and cryogenic transmission electron microscopes, we might have unearthed a new undocumented feature of Outlook. And that made it “edutaining”. 😊