with this code (config.xml on my custom module):
<core>
<rewrite>
<email_template>Company_Pluginname_Model_Email_Template</email_template>
<email_template_mailer>Company_Pluginname_Model_Email_Template_Mailer</email_template_mailer>
</rewrite></core>
I override successfully the first model (Mage_Core_Model_Email_Template). But the second, Mage_Core_Model_Email_Template_Mailer not works... why? Thanks!