We have a custom built Visualforce page that was created to allow our users to mass email contacts. Currently, when a user creates a list view of contacts to email and clicks the "Send Email" button, they receive an error saying, "Collection Size 16,972 exceeds maximum size of 1,000."

When I go under Setup --> Administer --> Communication Templates -->  Email Templates, I can see that there are thousands of email template for mass emails that were sent using Marketo. Everytime a user sends a mass email using the "Send Marketo Email" button, a template is added to the "Marketo Email Templates" folder. So, if a user sends a Marketo Email to 5 contacts, 5 templates are added to the folder.

I am not a developer, so I am confused as to why each email adds a template to this "Marketo Email Templates" folder.