I have re-checked my test site which is under Joomla! v2.5.7.
The email icon does show.
So either the module does not get styled as a whole or there is a conflict of some sort.

Hello,
is there a URL I can look at? It may just be a CSS override but I cannot tell until I see the code.
Thank you!

Naj,
there is a problem with the obfuscation of the email addresses. This bug happens when the module is included into a plugin (like loadmodule). In order to avoid this issue (Joomla-related), you should use the Trombinoscope menu item to show the contacts into the content. It will even give you more options (pagination among other things). It seems like this is all you need here.