I wonder now if there is any other way than just this to prove you are the owner of a given address? I mean technically someone could post on social media that they own a certain address and that they were going to make a transaction at a certain time at a specified amount and linked to the outgoing wallet or something....
Besides signing messages, a valid email is one way to prove ownership of your account. This may require involvement of an admin or recovery team and you must provide everything necessary to verify that it is you.
Additionally, an IP address can also be one of several ways to recover your account and prove ownership. Just like email, it requires admin and recovery team involvement to verify it.
Use a new email account, an email forwarding service, or similar. Do not use a "disposable" email account, as email resets to publicly-accessible disposable emails is a common cause of accounts getting stolen. It is also currently possible to use a fake email like
asdf@invalid.bitcointalk.org, and we may allow signing up without an email address in the future. However, if your account has never had a valid email address, then it will be extremely difficult to recover the account if it is ever stolen.
IP-address retention
You can opt into limited retention in your account settings. This will apply only to logs created after you change the setting, and doing so will make it much more difficult for you to recover your account if it is ever lost.