I didn't get a reservation email I'd like to know how to resend the mail again

Please check in your Interrail account, in the Reservations Overview. Your reservation should be visible there, with a button to download the reservation. As far as I know, there's no button to resend the mail.

If you don't see your reservation there, then contact customer service:

https://eurail.zendesk.com/hc/en-001/requests/new

Include details of which train(s) you booked and for which date(s).