A strong proof of ownership would be to provide us a signed message from the addresses you used in your signature campaigns.
1HtKTUrK5EQ7nnVdxBGxKQ7sLDAHSDfRkC
1M5hBG8SPUK3TgQ3xRT1spNup73MrNdfV7
16eJB47zFE1PaRCUhc4p7mSHdXHeTPwb5P
17E2sqhwU4PHhmZSo6pKQ9NZa2T6kQ1sJV
19Y4NSiG8kkzwWjMD17euEaQ5PErpwxWkP
1Cug98uWYXTJrbtKzFTFKM2Ug9JvLr767m
1DAPu2HxEoSsQhajg37jqfkVgWge99Gd5N
I got those from
ninjastic.space. You may be assisted from the admin of this place even if you don't prove it this way, though. You didn't stake an address that would speak for itself as a proof anyways.
I guess that owning the old email may be enough for you to get it back.