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

I have been doing some more investigation. It seems this is an IMAP issue that effects all Outlook accounts not just o Mac. If the IMAP gets any corruption on either end (a missing email) it will have trouble synching. It seems to recognize that something is different between the two accounts and then reloads the account to solve the issue. So keeping the size of the overall account down is the only solution. To solve mine I am archiving the last 5 years into a separate file. I can reload it if I need to for some reason. I believe this will solve the problem.

Dale Fowler -

Your advice helped me resolve my problem. I reduced my main InBox from >7,000 messages to under 2,500, either by deletions or moves to sub-folders. Ever since taking this step, the Outlook connection stabilized: I no longer see any reloading off my Outlook mailbox folders. Thank you Dale!

Doug

Just wanted to say that I have had this exact same issue with Outlook 2016 for Mac since I installed it on my 2016 MacBook Pro a few weeks ago.

My email is hosted with my website hosting company, Fat Cow, so in case anyone thinks it's associated with iCloud or gmail or something like that, I have proof that it happens with an independent email server.

I have spoken to Microsoft on the phone about it a few times recently, most of the time I share my screen with them and they check things and maybe even trash my plist file. But so far, nothing has cured the issue.

I noticed that there was an update for Outlook recently, just after I spoke with a Microsoft tech support person. I installed the update, and for a few minutes it felt like maybe this update was going to fix the issue. 

But, no such luck. After a little while, there went the error message, there went my folders, and there went my hope of being able to use rules again.

If I didn't want to sort my email and put it in the appropriate folder automatically (as I have since the beginning of email, if I recall correctly), it wouldn't bother me so much.

But since I DO want to have emails appear in the appropriate folders, I sure would like to be able to use those rules again!

Please, Microsoft, do something about this obviously widespread error!

thanks!

Hi everyone. I have had the same problems for 3 years. It is not an update issue and it is not fixed by updates. I notice that some weeks are very bad and others are fine. I have two accounts linked to my Outlook. It only effects one of the accounts so I am inclined to believe that it is an ISP related problem.

My only suggestion is keep your inbox and sent box small by using subfolders. This way you only reload 200 emails instead of 5000. Also, when moving emails to folders I suggest doing this offline. Moving emails is a trigger for the error message. I hope this work around helps you. This keeps me sane as I have never found a solution to the problem.

Hi,

I am not sure that this is an ISP problem... I have two emails connected to my outlook and they both have the same problem.

Dale, trying to keep InBoxes small sounds like an idea with merit. I'm not so sure I want to shift to off-line mode to file emails in sub-boxes, constantly switching between connected to the Internet or not. Thanks for sharing your thoughts and workarounds!

• Doug