backup email address; substitute email address
A secondary email address used for account recovery, verification, or as an alternative contact.
See also: サブ
Please enter a backup email address when registering your account.
If you forget your password, a reset link will be sent to your substitute email address.
Explicitly segmented spelling with interpuncts; rarely used in practice.
Loanword compound from English 'sub' + 'mail' + 'address', referring to a secondary email address.