Email address is a required field for all Marketo leads. However when my team imports a list, if their is a lead with email empty, but other fields are filled (name, address, etc), Marketo will create a new lead ID. How can I block empty email address leads from importing into the system from a list? It's creating useless leads in the database.
I do not believe you can block it outright.
But you could setup an instant alert or cleaning smart campaign.
If lead is created and email address is empty, the flow step would be to alert you so you can review it, or the flow step could be to delete the lead so you wouldn't have to worry about it.