Outlook stops responding frequently - on premise exchange

Question

We have an on premise exchange environment with mostly Microsoft 365 (some H&B) with all Windows 10.

We have a user that reports very frequently that Outlook stops responding. It can be during various tasks, such as opening an email, starting a new one, playing an audio attachment, opening a photo, or even searching. They do get a lot of multimedia attachments for their job. It will throw an error in event viewer but I'm not sure how to decipher it for any meaning why. We have investigated add-ins extensively, ran the office repair both online and offline, created new outlook profiles, tried safe mode, ran SaRA, we changed out (brand new) laptops and even created a new AD account (with the same alias). Yet the same problems keep occurring. We opened a ticket with M365 support but they were unable to figure it out and referred us to contact Outlook desktop support directly but didn't provide a contact. We even replaced M365 Outlook with H&B16 Outlook and it still keeps crashing multiple times daily. This is by far the worst case in our environment. We do have a few other users that report occasional-somewhat frequent crashing/locking up but nothing this bad (or at least so they tell us).

(question moved from Microsoft Community per moderator's request)

Answer 1

Hi @Abe Schreier ,

I noticed the issue only occurred on any specific users, are there any differences between them and others who could work normally in Outlook(such as mailbox size and others)? Could this user work normally on owa?

Also, what's the working mode of the exchange account in Outlook client(cached exchange mode or online mode)? If you switch to another mode, Are there any differences after that(File>Account setting>Account settings>double-click the account>cached exchange mode)?

According to your description, the issue could be reproduced on Microsoft 365 Outlook and H&B16 Outlook in new laptop, it may be related to your account instead of your client. Based on my research, I found a relevant document that mentioned you may experience Outlook performance issue when you have lots of items in any single folder or have lots of mail folders , please kindly check if it's also your case:

Outlook performance issues when there are too many items or folders in a cached mode .ost or .pst file

If your issue has any update, please feel free to post back.

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