connection failes pop.ionos.com

[foxjazz]

var mc = new OpenPop.Pop3.Pop3Client();
string hn = "pop.ionos.com";

        mc.Connect(hn,110,true);

[jstedfast]

The problem you are hitting is that port 110 is not an SSL-wrapped port. You either need to pass false as the useSsl argument or you need to use port 995.