Error sending with gmail an epub book!

[christophe rhein]

Hello,
I tried to send a book by mail using the build in e-mail fonction but I get this error message:
ERROR: L'envoi par email des livres a échoué: L'envoi par email des livres suivants a échoué:

TransformerdocumentePub

'ascii' codec can't encode character u'\xe8' in position 5: ordinal not in range(128)
Traceback (most recent call last):
File "/usr/lib/calibre/calibre/gui2/device.py", line 588, in _send_mails
attachment_name = attachment_names[i])
File "/usr/lib/calibre/calibre/utils/smtp.py", line 179, in compose_mail
attachment_name=attachment_name)
File "/usr/lib/calibre/calibre/utils/smtp.py", line 29, in create_mail
msg = MIMEText(text)
File "/usr/lib/python2.6/email/mime/text.py", line 30, in __init__
self.set_payload(_text, _charset)
File "/usr/lib/python2.6/email/message.py", line 224, in set_payload
self.set_charset(charset)
File "/usr/lib/python2.6/email/message.py", line 260, in set_charset
self._payload = self._payload.encode(charset.output_charset)
UnicodeEncodeError: 'ascii' codec can't encode character u'\xe8' in position 5: ordinal not in range(128)

What did I wrong?
Thank you!
Christophe