Outlook keeps freezing/crashing when using a Shared Mailbox (both email & calendar.)

Question

Hello,

I am on a company profile using Microsoft Outlook App (Office 2016). We have a shared mailbox that is currently only shared between myself and a colleague and is not a frequently used email account, as of yet. We would like to use it more, but the slowness and crashing is really affecting our ability to be productive.

Every time I go into the mail or calendar (those are the only 2 I use), Outlook freezes for a very long time, doesn't action what I was trying to action, and/or crashes. Even just clicking on it freezes the system. Trying to switch between my inbox and the shared inbox leads to at least (at a minimum) 5 minutes of nothingness and then either crashes or is extremely slow. I have used shared inboxes in the past without this issue.

For more context:

• The other user barely uses it, he is a backup.
• Mail Folder Size: 2KB; Total size: 515,319 KB
• Calendar Folder Size: 119598; Total size: 119598 KB
• I have not added any add-ins. Admin-Managed: Report Message; My Templates; Action Items.

Can anyone help?

Answer 1

A corrupted search index can cause slowness. Rebuilding it might help:

Go to File > Search Tools > Indexing Options.

Click Advanced > Rebuild.

Choose your mailbox data file and click OK.

• Consider repair Outlook 2016 via Control Panel.

Answer 2

Hi @Caroline Roy ,

If the Download Shared Folders option is enabled in Outlook, the contents of the site mailbox are synchronized to your local .ost file. This can result in an increase in size for the .ost file as well. Please check by the following steps:

1. In Outlook, select File >Account Settings >Account Settings.  You will see a list of your email accounts.
2. Select the Microsoft Exchange account that you use to manage someone else's calendar and choose Change...
3. Choose More Settings, followed by the Advanced tab.
4. Click to clear the Download shared folders check box.

The damage of the profile may also cause this problem. It is recommended that you create a new profile and re-add account to see if the problem will be reproduced: Go to Control Panel > Mail > Show Profiles, add a new profile and then re-add the account.

If the issue continues, I want to confirm how the shared mailbox is opened, such as being opened manually as an additional mailbox or being opened because of Automapping.

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