Can you be more specific?
Which API ?
When you say "emails" do you mean Leads, or do you mean the Email Asset?
I am currently trying out a Launchpoint application called Data Loader for Marketo to help me extract Lead and programs data into MS SQL. It is quite convenient and easy to use, so maybe you can give it a try as well. You can find some discussion regarding this tool in the community. Hope this would help!