Phishing warnings will occur when, in the HTML part of an email, images are referenced where the domain in the image path does not match the sender domain used. An example: the sender domain is newsletter.company.com whereas the images are located on a server with the URL http://www.myserver.com/img/image.jpg. The same problem can occur when links with differing URLs are used. False subdomain configuration settings might be another possible cause for this problem.
Posted in: Email clients