One way to do this is to create an email address (and email handler) in Salesforce to add to the BCC the emails out of Zuora. With the CRM ID available somewhere in the email (header, subject or body), the email handler can attach the email to the Salesforce account.
The cleanest solution would have the CRM ID in the email header (hint, hint Zuora).
Another idea is if the email and callout history was available via API, then one could query it from Salesforce as needed rather than syncing the entire history into Salesforce. Sync has its advantages when you need to run reports or query based on the information, but email history (at least for our use cases) is generally visiting an account and looking at the email history (or at most wanting to search through an accounts emails). Thoughts?
