I sent an email to a website's contact and my mailserver received this error:
<...@...>: host ....mail.protection.outlook.com[22.214.171.124] said: 451 4.4.4 Mail received as unauthenticated, incoming to a recipient domain configured in a hosted tenant which has no mail-enabled subscriptions. ATTR5 [BN7NAM10FT047.eop-nam10.prod.protection.outlook.com 2023-07-09T02:31:08.020Z 08DB7EF866B08CFF] (in reply to end of DATA command)
So now Microsoft has logs of this email I sent, but they were never (or are no longer) charged by the owner of the domain name with the task of handling the incoming email. (The MX record for the domain points to a mail.protection.outlook.com subdomain, so this seems a mistake of the DNS admin. But something similar may happen in absence of a MX record if my mailserver defaults to the A record and the host accepts connections.)
Who's the data controller?