Currently, we are going through the process of migrating from emailaddress to unique identified ID for our subscribers as SubscriberKey in SFMC.
We have unique identifier for all our existing customers (ID that is being used internally across all applications) BUT we have some campaigns where we are collecting email address using cloud pages (smart capture) and triggered emails. In other words, these entries are NOT from existing customers (i.e. leads / prospects).
If we continue to send email to these entries from SFMC, they will be added to All Subscribers with subscriberkey as emailaddress as that is the only known information available at the time of form entry (they are not customers yet). Hence, we will always end up with subscribers without unique identified in the SFMC contacts.
How to go handle leads / prospects so that we can still avoid emailaddress as subscriberkey?
Is it possible to generate unique leadID and use it as subscriberkey and when they become a customer, we swap subscriberkey from leadid to internal customer ID?
Again, we DO NOT have any CRM connected (so salesforce.com connection is not applicable in this case).