ViralURL.com 3.0 Campaign & Conversion Tracking ... https://www.youtube.com/watch?v=i7g_qJdjJhE

Gmail Links Tip. Update April 28th 2015: Google has fixed this problem since back when I reported about it first, but I noticed that these days, uppercase letters in the domain name part of your links can cause Google to deliver the email into the spam box. So it's still better not to use uppercase letters in the domain name part of links inside your emails. If you send HTML emails, you can use upper case characters (in the domain name) in the anchor text part, just not in the href of the link. ... https://www.youtube.com/watch?v=3Qy5Pzd_g-o