Hi,
Did the user configure the mailbox with cached Exchange enabled in Outlook? If so, please try turning off cached Exchange mode first, then try the 'Empty Auto-Complete List' under File > Options or try starting Outlook with 'outlook /cleanautocompletecache'
command to see the result. The Auto-Complete entries are stored in your mailbox and cached to local, it could be that when clearing the Auto-Complete list with cached Exchange mode enabled, it didn't correctly clear the source entries stored in your mailbox.
Regards,
Steve Fan
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