Mail chimp API isn't up to Apple's default security standards for iOS 9

[lewis-smith]

https://developer.apple.com/library/prerelease/ios/technotes/App-Transport-Security-Technote/

Work around:

Add the following to info.plist

     <key>NSAppTransportSecurity</key>  
     <dict>  
          <key>NSAllowsArbitraryLoads</key><true/>  
     </dict>  

[ollieatkinson]

You don't want to do this, you should explicitly define the URL's you allow the system to use.