As a vendor you can see the autoresponders that integrate with JVZoo in the product editor. The options currently are GetResponse, Aweber, SendReach, SendLane, MarketHero, and ImnicaMail.
As an affiliate, you are only able to use GetResponse through the JVZoo system.
Vendors have other options, because they are doing the programming for their own sites, but affiliates are limited at this time.
You can also create your own integration, by using the IPN forwarding section to integrate: https://jvzoo.zendesk.com/hc/en-us/articles/206456857-JVZIPN-Create-your-own-integrated-script-
You can also include a squeezepage within the delivery system and have your customers manually enter their email. Currently these are the only ways to use a non-supported Autoresponder.