We have just released OSDownloads 1.3 with several great new features.
The most important new feature in OSDownloads Pro is email validation. Now you can email download links to users. This makes sure that they enter a valid email address.
If someone does enter valid email address, you can automatically add them to your MailChimp list.
On the other hand, if they enter a fake email address or don't click the link, they won't be added to MailChimp.
You can also disable this feature for logged-in users (because they have probably already confirmed their email address).