« How can one link / merge / combine / associate two accounts / users? (Anonymous / unregistered / cookie, or Google / Facebook / registered) » pretends to deal with account merge for « Anonymous / unregistered / cookie » users.
But it also mentions « After you contact us, the Stack Exchange Team will reach out to verify that you own both accounts. If we can confirm your ownership, we will initiate a merge. »
Having done so, not the Stack Exchange team, but obviously a robot sent a mail to one of the account's email: I had to click a link to confirm my request. But the other account's email has no email when it is a cookie-auth account.
How does the Stack Exchange team reach out to the no-email-account's user?
(It seems the proposed procedure doesn't deal with this part of the question / of the possible situation = Regain access to account .)
All in one sentence: « When the merge-robot has to reach out both account's contacts to check that "both" agree to merge, how does he manages this for a cookie-only account? »