Binary file email attachment problem

[Alan Harris-Reid]

Hi there,

Using Python 3.1.2 I am having a problem sending binary attachment files 
(jpeg, pdf, etc.) - MIMEText attachments work fine. The code in question 
is as follows...

for file in self.attachments:
   part = MIMEBase('application', "octet-stream")
   part.set_payload(open(file,"rb").read())
   encoders.encode_base64(part)
   part.add_header('Content-Disposition', 'attachment; filename="%s"' % 
file)
   msg.attach(part)   # msg is an instance of MIMEMultipart()

server = smtplib.SMTP(host, port)
server.login(username, password)
server.sendmail(from_addr, all_recipients, msg.as_string())

However, way down in the calling-stack (see traceback below), it looks 
as though msg.as_string() has received an attachment which creates a 
payload of 'bytes' type instead of string.  I suspect the error lies in 
the encoding somewhere, but I've no idea where.  I have also tried 
MIMEApplication and MIMEImage, but the error still remains.  I have seen 
many similar code examples on the web, all of which fail for me, so I 
wonder if there is something wrong with my environment.

Has anyone any idea what might be causing the problem? Any help would be 
appreciated.

Alan

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builtins.TypeError: string payload expected: <class 'bytes'>
File "c:\Dev\CommonPY\Scripts\email_send.py", line 147, in send
  server.sendmail(self.from_addr, all_recipients, msg.as_string())
File "c:\Program Files\Python31\Lib\email\message.py", line 136, in 
as_string
  g.flatten(self, unixfrom=unixfrom)
File "c:\Program Files\Python31\Lib\email\generator.py", line 76, in flatten
  self._write(msg)
File "c:\Program Files\Python31\Lib\email\generator.py", line 101, in _write
  self._dispatch(msg)
File "c:\Program Files\Python31\Lib\email\generator.py", line 127, in 
_dispatch
  meth(msg)
File "c:\Program Files\Python31\Lib\email\generator.py", line 181, in 
_handle_multipart
  g.flatten(part, unixfrom=False)
File "c:\Program Files\Python31\Lib\email\generator.py", line 76, in flatten
  self._write(msg)
File "c:\Program Files\Python31\Lib\email\generator.py", line 101, in _write
  self._dispatch(msg)
File "c:\Program Files\Python31\Lib\email\generator.py", line 127, in 
_dispatch
  meth(msg)
File "c:\Program Files\Python31\Lib\email\generator.py", line 155, in 
_handle_text
  raise TypeError('string payload expected: %s' % type(payload))

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