[closed] Email notification not working: 'ascii' codec can't encode character u'\xf3' ordinal not in range

When I post a new question or comment or answer the content it is correctly inserted but the notification is not sent. The log shows this error:

/opt/osqarh/forum/templatetags/extra_tags.py TIME: 2011-09-01 12:36:02,214 MSG: extra_tags.py:render:243 Error in declare tag, when evaluating: html.objlink(comment.author, style=settings.EMAIL_ANCHOR_STYLE)
/opt/osqarh/forum/models/action.py TIME: 2011-09-01 12:36:02,215 MSG: action.py:trigger_hooks:195 Error in CommentAction hook: 'ascii' codec can't encode character u'\\\\xf3' in position 7: ordinal not in range(128)
/opt/osqarh/forum/models/action.py TIME: 2011-09-01 12:36:02,215 MSG: action.py:trigger_hooks:196 Traceback (most recent call last):
  File "/opt/osqarh/forum/models/action.py", line 192, in trigger_hooks
    hook(action=action, new=new)
  File "/opt/osqarh/forum/subscriptions.py", line 99, in comment_posted
    send_template_email(subscribers, "notifications/newcomment.html", {'comment': comment})
  File "/opt/osqarh/forum/utils/mail.py", line 29, in send_template_email
    t.render(Context(context))
  File "/usr/local/lib/python2.6/site-packages/Django-1.2.5-py2.6.egg/django/template/__init__.py", line 173, in render
    return self._render(context)
  File "/usr/local/lib/python2.6/site-packages/Django-1.2.5-py2.6.egg/django/template/__init__.py", line 167, in _render
    return self.nodelist.render(context)
  File "/usr/local/lib/python2.6/site-packages/Django-1.2.5-py2.6.egg/django/template/__init__.py", line 796, in render
    bits.append(self.render_node(node, context))
  File "/usr/local/lib/python2.6/site-packages/Django-1.2.5-py2.6.egg/django/template/__init__.py", line 809, in render_node
    return node.render(context)
  File "/opt/osqarh/forum/templatetags/extra_tags.py", line 241, in render
    context[m.group(1).strip()] = eval(m.group(3).strip(), d)
  File "<string>", line 1, in <module>
  File "/opt/osqarh/forum/utils/html.py", line 72, in objlink
    return hyperlink(settings.APP_BASE_URL + obj.get_absolute_url(), unicode(obj), **attrs)
  File "/opt/osqarh/forum/utils/html.py", line 69, in hyperlink
    return mark_safe('<a href="%s" %s>%s</a>' % (url, " ".join('%s="%s"' % i for i in attrs.items()), title))
  File "/opt/osqarh/forum/utils/html.py", line 69, in <genexpr>
    return mark_safe('<a href="%s" %s>%s</a>' % (url, " ".join('%s="%s"' % i for i in attrs.items()), title))
  File "/opt/osqarh/forum/settings/base.py", line 42, in __str__
    return str(self.value)
UnicodeEncodeError: 'ascii' codec can't encode character u'\\\\xf3' in position 7: ordinal not in range(128)

How can i fix this?