Admin emails not formatted

Hi.
I'm configuring the different emails that the shop sends.
No problem with the emails from the shop, i can use html tags and they display properly on received.
But for emails from admin (like updates emails from product > history) i can't use HTML tags, they appear as is on the got email.

Any solution for this? Is about some server configuration i need to do?
I'm running OC 1.5.5.1

Thanks in advance.

Anyone?