The following steps might be helpful. Although the following steps might not be exactly what you want, I think they are close.

"Settings". > "Accounts" section. > Tap the account you want to configure. > "Sending mail". > "Composition defaults". > Enter one or more email addresses in "Bcc all messages to" field. If you want to enter multiple email addresses, separate email addresses with commas. > Tap "SAVE" on the top right corner.