Often we replace Outlook profiles or just OSTs, but there is a much different step. After making sure there are no Outlook.exe processes running, go to the user’s Windows AppData folder:
Roaming\Microsoft\Outlook under there, and rename it to Outlook.OLD. Do the same for
Local\Microsoft\Outlook if that’s there.
The results are likely to be different :-) You may possibly, also, not have to create a new Outlook profile after doing this. It seems to cause Outlook to replace files which are being corrupted relatively often. This also fixed some mystery IMAP behavior where sync was reported complete but did not bring in new email.
For a very long time, it was thought gospel that Outlook had hard caps on size of PST and OST files, which equals a hard cap on the size of a mailbox that Outlook can see. This has, apparently, changed. 100-gigabyte OSTs are possible, and larger. It is thought that very fast hard drives primarily, and certainly also good CPU and lots of RAM, are needed to reliably handle huge mailboxes and PSTs without corruption. Here is a method by registry entries. It’s also possible by Group Policy.
Today it was found that an Office 2019 installation via 365, did not have any of the registry keys involved. After creating them manually in Regedit, the desired results did occur. These very registry entries are also created by the Group Policy method.
Once you install the Office 2016 templates:
you can set the maximum sizes:
This creates the same registry entries as the manual method.
As of version 2019 (and possibly before), QuickBooks has a new feature: native support of Office 365 webmail and some other major email providers. When users send email via QuickBooks, go to Preferences, Send Forms, and instead of choosing Outlook, choose Webmail, and then set up integration with the user’s Exchange Online account. Works much smoother, faster, more reliably.
Sometimes, newer versions of Outlook will hard-fail a plugin, so that none of the standard GUI changes will permit it to reenable. When this happens, you can override by deleting everything here:
This does enable every plugin, so there is a bit of danger.
At long last, as found by the astonishing Tharin Brown, we are given an Outlook repair tool that really works!!!: