Favicon when sending email from your site

How to make when sending a message from your site, has the user near the address of the sender Was a favicon site from which the message was sent?
I tried to indicate in & lt; Head & GT; The letter has the address to Favicon.iso, but the mailers ignore the tag & lt; Head & gt;.

Answer 1, Authority 100%

Do you understand that it’s just not to add the icon so that your site would have been social. Network or something kapets-pipets popular.