My Marketo sync user in SFDC has some sharing rules in place that restricts records without an "@" symbol in their email address from syncing with our Marketo instance. However, the problem that I run into is when a records syncs to Marketo and then sometime down the road a sales rep deletes the email out of salesforce. This causes the sync to break, and the record not to be updated in Marketo. This seems to happen when a record leaves a company and the email gets deleted.
Any suggestions on how to manage this? I can remind the sales rep not to do that, but curious if anyone has experienced this or something similar and how you managed it.
An Apex trigger is one way. I would say once you have an email address for a record, deleting it completely rather than marking it as future-unusable is poor practice. Otherwise, you have no way to correlate old emails (inbound or outbound) with a known contact.