Hi,
How was the autocomplete list got wiped out? Auto-Complete cache is stored in a hidden message in your mailbox. If the autocomplete cache has been wiped out and the changes have been synced to the mailbox, I'm afraid it's not possible to restore it.
You may try to create a new mail profile and then configure the email account in the new profile to see if the Auto-Complete cache still persists.
Besides, we may also try restoring the AutoComplete list from the RoamCache folder if the cache hasn'r been removed from the folder:
https://www.msoutlook.info/question/844
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Regards,
Steve Fan
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