is there any way to know what account are connected with an email?

i know i had old accounts, and i'm pretty sure i used my email.. but i can't recall the names.

any way to do this?

if you registreted your accounts, you received notification in your mailbox about realm and acc name.
However, you need to know that email adress but if you deleted messages before - no help ^^

you can try to use X account name with X email, you'll know if it works because you'll receive an email about it

or just search your email inbox for d2 notifications