Originally Posted by Konda

Outgoing links don't have to be https, the only thing that will trigger a warning is when you include a non secure item (such as a js file or iframe/ad code or image). Any reputable ad network, counter, third party plugins, etc. offer https. If you use any sponsor, ad network, counter, js, etc. that doesn't in 2017 I would leave them asap, because they obviously don't take MARKETING seriously, so I wouldn't trust them with anything.