That may not be a good idea though. Considering someone can have their email compromised an attacker would have access to their wallet backup.

Also, anyone in between blockchain email servers and OP's email would also be able to intercept the wallet. Hopefully the wallet has a very strong unique password. Even with a strong password though, you are opening yourself up to a bruteforce attack without any type of notification until it's too late.

If you are using a blockchain wallet make sure you have a long unique password and that you are downloading the backup directly from their site and it is in your best interest to not use the email backup feature. Be sure to enable 2 Factor authentication while you are at it.

If you do wind up using the email backup feature be sure to use a strong unique password on the email account and to enable 2FA if you can.