Error in e-mail - Intervention

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Por favor, complete los pasos para reproducir el error aquí:
Create an intervention, then gave send mail and get the error

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Exception

UnicodeEncodeError: 'ascii' codec can't encode character u'\xf1' in position 22: ordinal not in range(128)

Traceback

File "/usr/lib/python2.7/dist-packages/zope/publisher/publish.py", line 132, in publish
  result = publication.callObject(request, obj)
File "/usr/lib/python2.7/dist-packages/zope/app/publication/zopepublication.py", line 205, in callObject
  return mapply(ob, request.getPositionalArguments(), request)
File "/usr/lib/python2.7/dist-packages/zope/publisher/publish.py", line 107, in mapply
  return debug_call(obj, args)
Extra information: schooltool.skin.flourish.zcml_content.FlourishInterventionMessageAddView_addMessage.html object at 0x7f9ddf714f90
File "/usr/lib/python2.7/dist-packages/zope/publisher/publish.py", line 113, in debug_call
  return obj(*args)
File "/usr/lib/python2.7/dist-packages/schooltool/skin/flourish/page.py", line 70, in __call__
  self.update()
File "/usr/lib/python2.7/dist-packages/schooltool/skin/flourish/form.py", line 72, in update
  super(AddForm, self).update()
File "/usr/lib/python2.7/dist-packages/schooltool/skin/flourish/form.py", line 55, in update
  super(Form, self).update()
File "/usr/lib/python2.7/dist-packages/z3c/form/form.py", line 211, in update
  self.actions.execute()
File "/usr/lib/python2.7/dist-packages/z3c/form/action.py", line 99, in execute
  result = handler()
File "/usr/lib/python2.7/dist-packages/z3c/form/button.py", line 315, in __call__
  return handler(self.form, self.action)
File "/usr/lib/python2.7/dist-packages/z3c/form/button.py", line 170, in __call__
  return self.func(form, action)
File "/usr/lib/python2.7/dist-packages/schooltool/intervention/browser/intervention.py", line 1121, in handleAdd
  email = sendmail.sendInterventionMessageEmail(obj)
File "/usr/lib/python2.7/dist-packages/schooltool/intervention/sendmail.py", line 64, in sendInterventionMessageEmail
  return sendEmail(sender, recipients, subject, body)
File "/usr/lib/python2.7/dist-packages/schooltool/intervention/sendmail.py", line 196, in sendEmail
  utility.send(email)
File "/usr/lib/python2.7/dist-packages/schooltool/email/mail.py", line 193, in send
  message)
File "/usr/lib/python2.7/smtplib.py", line 736, in sendmail
  (code, resp) = self.rcpt(each, rcpt_options)
File "/usr/lib/python2.7/smtplib.py", line 488, in rcpt
  self.putcmd(rcpt, TO:%s%s % (quoteaddr(recip), optionlist))
File "/usr/lib/python2.7/smtplib.py", line 341, in putcmd
  self.send(str)
File "/usr/lib/python2.7/smtplib.py", line 328, in send
  self.sock.sendall(str)
File "/usr/lib/python2.7/ssl.py", line 329, in sendall
  v = self.send(data[count:])
File "/usr/lib/python2.7/ssl.py", line 298, in send
  v = self._sslobj.write(data)

Modules

schooltool 2.8.5 (/usr/lib/python2.7/dist-packages)
schooltool.cando 2.8.2 (/usr/lib/python2.7/dist-packages)
schooltool.gradebook 2.8.4.1 (/usr/lib/python2.7/dist-packages)
schooltool.intervention 2.7.0 (/usr/lib/python2.7/dist-packages)
schooltool.lyceum.journal 2.8.2.1 (/usr/lib/python2.7/dist-packages)

Runtime

Python 2.7.6 (default, Jun 22 2015, 17:58:13)
[GCC 4.8.2]
Linux pcusuario3 3.19.0-51-generic #58~14.04.1-Ubuntu SMP Fri Feb 26 22:02:58 UTC 2016 x86_64 x86_64
Filesystem encoding UTF-8, preferred UTF-8