Mac Outlook Slow

Mac Outlook Slow: a reader asks…

I have Office 365 running on my Macbook Pro, and Outlook is running very slowly. Also, anytime Outlook is running I get a hooting sound every few seconds. Is there an Office repair feature like there is on Windows?

After a few back and forths, it turns out the reader had an email stuck in their Outbox, and that email had somehow been corrupted or mis-addressed. Outlook kept trying to send the email out, and the (Microsoft Exchange) server kept rejecting the mal-formed email. That caused two things:

  1. Outlook was chewing up a lot of memory, CPU and other resources trying to get that email sent out. This slowed down the computer for everything else they wanted to do.
  2. Outlook notifications have a sort of hooting sound that you hear each time there’s a Sync error. This is by design, although it can be disconcerting if the notification keeps going off every few seconds.
Outlook for Mac Sync Status buttons

The solution was to delete the email from the Outbox. That instantly stopped the sync error sound, and lo and behold, Outlook (and the Macbook Pro in general) started operating normally again. Outlook’s menu bar has a Sync Status button which can show you what’s happening. Watching that status window showed a new error pop up every few seconds, timed right along with the hooting notification sound.

The second clue was that there was an Outbox entry on the list of folders on the left-side of the Outlook window. Normally that isn’t displayed, it only shows up when there are unsent emails in the Outbox. The combination of these clues pointed towards a problem with an unsent email that was sitting in the Outbox, which Outlook kept trying to send.

Diagnosing problems with modern computers can be an exercise worthy of a Sherlock Holmes, with barely visible (or audible) clues that point the way to a solution. It’s a sign of our times that the software developers (engineers) who create the programs we use very often don’t think much about the average user’s experience. Hopefully as software continues to mature, this problem will resolve itself.

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  1. Sanjay Bhowmick

    Hi Chris: I am having a similar problem. No hoot, no outbox but my Outlook 16.41 is very slow on my macbook pro and also seems to slow down everything else with the spinning wheel, slow type, slow to register a click.. I used Outlook through my employer site but after a recent cyber attack on the organisation’s serve I have accessed n=my office emails on Outlook from Outlook I had on my Applications folder and updated to 16.41. Since then I have been having this problem. I am also not getting the features I had on Outlook like replying in the preview and other functionalities. Can you help? Many thanks.

    • Hi Sanjay, the current version of Outlook is 16.43, and you should update (assuming you have an active Office 365 subscription). If you purchased Outlook or MS Office as a stand-alone product (not as a subscription), then you may or may not be able to get the latest version.

      You don’t give me much information to diagnose the issue, and often these kinds of problems need to be dynamically diagnosed. Since you’re accessing office emails, you should be tapping into your office tech support to help you with this.

      So some wild guesses: Your copy of Outlook may not be activated, which would limit the functionality. If you click Outlook > About Outlook you should see a license key, or it may show as unlicensed. Your office may have security settings in place (assuming they’re using MS Exchange Server), are running an old version of Exchange Server, or have server configuration issues (esp. possible if they’ve been hacked). If Outlook is connected to your office Exchange server, then you’re at the same mercy of data since your Outlook is synchronizing with the server – if the server has problems you will also.

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