Please use a personal email. My email is ‘mail’ @ ‘my actual name’. It does not get more personal than that
But you can’t use emails starting with mail@, admin@, support@, info@, main@, etc.
Instead they advised me (3 times) to create a personal email on a service like Yahoo, Outlook, Gmail, Orange, etc
I don’t think the reason they’re being used is relevant to their problem though. “Think like an attacker” wins the day here: as an attacker, I don’t care what it’s meant for, only how I can use it to my advantage. If it’s something they observed as a problem, I understand why they would want to stop it.
As for “-”, yeah, I don’t have a particularly good explanation for that one except the assumption that it’s something similar to + addressing on a different service.