When I try to add my non-Google address as a Google account alternative email address, Google bars me with this:

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I'm unaware of any Google account with which my email address is already used, except as as a recovery address which I presume is not grounds for this bar (esp. considering Google allows an address to be added as a recovery address without the permission of the addresses owner).

How can I find out which Google account this address is already being used with?

Note: This is not answered by either of:

Add Google Apps Email to My Google Account Email Addresses

How to add alternate email to Google account given error "This address is already used with another Google account."

protected by Community Nov 21 '18 at 12:46

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