Binary file email attachment problem

Question

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. Has anyone any idea what might be causing the problem? Any help would be appreciated. Alan ``` builtins.TypeError: string payload expected: <class 'bytes'> File "c:\Dev\CommonPY\Scripts\email_send.py", line 147, in send server.sendmail(sel…

Accepted Answer

Ok - after much frustration and web-searching, I have found that the problem is a known bug that applies to Python 3.x, encoders.py, function encode_base64, which should read as follows...

```
def encode_base64(msg):
    """Encode the message's payload in Base64.

Also, add an appropriate Content-Transfer-Encoding header.
    """
    orig = msg.get_payload()
    encdata = _bencode(orig)

# new line inserted to ensure all bytes characters are converted to ASCII
    encdata = str(encdata, "ASCII")

msg.set_payload(encdata)
    msg['Content-Transfer-Encoding'] = 'base64'
```

The bug has been raised as issue #4768, and was escalated to critical status on 2010-05-10. Hopefully it will be fixed in the next version (3.1.3?)

Regards, Alan

Binary file email attachment problem

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