Is it possible to have 1 Subscriber (a single Subscriber Key) with 2 different Email Addresses? For example, the Subscriber has one address (emaila@gmail.com) for a newsletter and a second address (emailb@gmail.com) for account information.
Our thought was if a newsletter gets send to emaila@gmail.com the subscriber email address in All Subs is emaila@gmail.com. Then an account notification gets sent to emailb@gmail.com and the email address for All Subs is now emailb@gmail.com. I thought this could be handled through the Use as Root setting on a Sendable DE, but it looks like that was deprecated.
The use case is to allow a Subscriber to be communicated to different addresses for different purposes but still be tracked as a single Contact.
Best Answer
The options recommended:
Journey Builder sends (cause these are easy) can actually deal with these scenarios using Population as a main source of the channel identifier (email address) and then within the journey configuration you can actually overwrite that selecting the email address from event source data extension. Assuming that you have email address field there. More details here: http://help.marketingcloud.com/en/documentation/journey_builder/interaction_settings/
With email you'll need to overwrite the email address in the All Subs every time you need to "switch" to the new one. This is not recommended, doing this there is a potential to have clashes of the updates, complete invisibility of that process to the end users and incorrect details in the reporting (the reports are still tied to the email address including the Tracking section).
My overall recommendation is to change the sub-key, keeping current an attribute as common value between 2 personas while generating completely unique SK's for each email address. The sacrifice is only reporting at the business level - count of subscribers will not be a true representation of the contacts they have, but you can work around that through the centralized common DE (that will be population). You'll need to implement 2 data models, one supporting JB and another to be used for sends via Email studio.