Doesn't work when called from command line(drush, scheduled rules, etc)

I tried a lot of things to test this, and it seems that the HTMLMail module doesn't process the whole thing when called from emails generated automatically. The HTML itself comes, but without the CSS. And if you call the same email from the Drupal interface instead of shell, the email is sent correctly. There is something missing in this process.

I'm trying to find what is this related, but i don't know much about this module code yet. I'll try to figure out.