How to disable web links preview in mail.app

Every time I open an email that contains a URL, it automatically shows the content of the web page (or part of it) below the URL and inside the body (not in a micro window). It is really disgusting to see a summary of a web page in the middle of an email. I work with it and the major of the signatures of my contacts have a URL and this function splits the body completely.

Can anybody help me to disable this function???