Right now it's "all or none" to share emails with source stores for fulfillment. Some of our fulfillment partners require an email to complete more complex transactions (i.e. multi-step checkouts and sizing kits are sent as a first step in the purchasing process). So, these stores need an email address to complete the ordering process on their end...
We don't want all our Source stores to have customers emails for:
#1 they don't need to know our customer email
#2 they have automatic email flows that will confuse the customer since they only expect to hear from us