outlook 2016 on Mac - "Mailbox already exists" error.

Anonymous
2016-10-06T05:13:04+00:00

Error "mailbox already exists (0.000 + 0.000 secs)" - and outlook loses connection to IMAP server (shows empty account).

Then, either through manual intervention (clicking on another account and then coming back), or sometimes it just does it by itself, it "rediscovers" my IMAP mailbox and works OK... Until next time (falls over every ?? 30 minutes or so).

Using outlook 2016 on Mac, V15.26.1. This also happened on previous version.

Didnt used to be a problem. Just started about 2 weeks ago with no changes from my end that I am aware of!?! Upgraded to latest Version today. Made no difference.

Advice welcome!

Outlook | MacOS | Legacy Outlook for Mac | For business

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  1. Anonymous
    2016-12-27T14:29:53+00:00

    Same with me!  About 2 months both with my Macbook Air and my iMac.

    Reloads the IMAP inbox all day long and gives me the errors.

    I double-checked my settings and everything is ligit!

    I'm on 365 with 10.12.2 Sierra.

    Tried a new Outlook profile, tried regenerating the account, at my wit's end...

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  2. Anonymous
    2016-12-14T07:52:03+00:00

    I have the same problem for almost two months now...

    I have tried every thing but without success! even the support team of microsoft tried to take over my mac and figure out the problem without any results.

    I am now waiting to get any answers from them by calling every week for updates but their answer is always "We didn't get any answer form the mac department, we will call you tomorrow to with answers"..

    And I am waiting for this call for a week now.

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  3. Anonymous
    2016-11-27T17:56:02+00:00

    I also see this behavior, ever since upgrading Office 2010 to Office 365 Home (which includes Outlook 2016 for Mac, version 15.26). My Macbook Air is currently running El Capitan (10.11).

    Most days Outlook works just fine but 1-12 times a week I receive a set of "Mailbox already exists" error messages for my IMAP account linked to my Apple iCloud (.mac) account. Thi problem is solely with that IMAP syncing as I have a half dozen other IMAP accounts that never see this error.

    At the time the "Mailbox already exists" behavior is seen, all of my iClloud-relayed folders (Archive, Deleted Messages, Sent, etc.) all report errors complaining that the Mailbox already exists. The observed behavior:

       - all of the folders associated with the iCloud account go to a "0" count

       - these mailboxes then automatically start to reload (which can take a long time as my InBox has >5,000 messages in the iCloud account InBox)

       - on bad days, this cycle can repeat multiple times

    When this behavior occurs I often lose recent 'handling' actions to InBox items (deletions or filing into a subfolder). Basically, once a reload starts it reflects a failure to sync recent actions so they are lost. Additionally, many items are unavailable until re-loaded.

    There are times when the automatic reloading of the InBox and other iCloud-related (.mac account) folders doesn't happen on its own. When so, I have to restart the Outlook app or restart my MacBook Air.

    Again, have several IMAP accounts, and I only see this problem with my iCloud (.mac) account.

    As this is an Office 365 Home subscription, the version should be up-to-date at all times. Not sure what causes this instability nor how to get anyone's attention at Microsoft about it. Going to the local Microsoft Store for their Answer Desk assistance didn't result in any useful help.

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  4. Jim G 134.1K Reputation points MVP
    2016-11-01T16:02:17+00:00

    If I were troubleshooting this my next step would be in Outlook, toggle the Sync Status and Sync Errors window on by pressing Command-7 and then Command-8. Then just keep an eye on those windows for a while and see if any traffic going by looks problematic, especially when the problem occurs.

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  5. Anonymous
    2016-10-31T03:03:38+00:00

    Problem still persists. I have updated to all the latest versions of the OS and of the Office applications.

    Has anyone got a solution to this?

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