looking at the source:
django/core/mail.py:
def attach(self, filename=None, content=None, mimetype=None):
"""
Attaches a file with the given filename and content. The
filename can
be omitted (useful for multipart/alternative messages) and the
mimetype
is guessed, if not provided.
If the first parameter is a MIMEBase subclass it is inserted
directly
into the resulting message attachments.
"""
--
Thomas Guettler, http://www.thomas-guettler.de/
E-Mail: guettli (*) thomas-guettler + de