Hi Diego - I suggest this approach:
1. Use the contact form to send an email. Does it have this problem? If not, the problem is likely not Drupal core.
2. Experiment with the Email Example in the Examples Project, http://drupal.org/project/examples. Does it have this problem? If not, imitate it. If it does, file an issue.
-Randy
> Date: Mon, 16 Aug 2010 07:48:13 -0400
> From: earnie@users.sourceforge.net
> To: development@drupal.org
> Subject: Re: [development] Email content type UTF8 not acceptedI have tried with different servers and clients, and they all show charset iso-8859-1 in the email header.
>
> Diego G wrote:
> >
> > It seems like Drupal is changing the charset to iso-8859-1.
> >
>
> I doubt it.
>
> > Does anyone have any idea of what is causing this problem?
> >
>
> Maybe your web server or php settings for html markup. Or maybe even
> your mail server or mail client.
Which php settings do you mean? Where can I find it?
Diego