Python mail: encoded attachments are truncated

I'm using the following function to send an email message with two attachments in my python script:

import smtplib
from email.MIMEMultipart import MIMEMultipart
from email.MIMEBase import MIMEBase
from email.MIMEText import MIMEText
from email.Utils import COMMASPACE, formatdate
from email import Encoders

...

def sendMail(sender_name, to, subject, text, files=None,server="localhost"):
      assert type(to)==list
      if files:
        assert type(files)==list
      print "Files: ",files
      fro = sender_name

      msg = MIMEMultipart()
      msg['From'] = fro
      msg['To'] = COMMASPACE.join(to)
      msg['Date'] = formatdate(localtime=True)
      msg['Subject'] = subject

      msg.attach( MIMEText(text) )

      if files:
        for file in files:
# ************** File attaching - Start **************
                part = MIMEBase('application', "octet-stream")
                part.set_payload( open(file,"rb").read() )
                Encoders.encode_base64(part)
                part.add_header('Content-Disposition', 'attachment; filename="%s"' % os.path.basename(file))
                msg.attach(part)
# ************** File attaching - End **************

      server.set_debuglevel(1)
      server.ehlo()
      server.starttls()
      server.ehlo()
   开发者_运维百科   server.sendmail(fro, to, msg.as_string())
      server.quit()

I get the mail, and the attachments are there, but for some reason, they are truncated a bit. My guess is I'm missing something in the encoding process.

For example:

Attachment 1: Original file byte count is 1433902, while the new byte count is 1433600

Attachment 2: Original file byte count is 2384703, while the new byte count is 2383872

Any ideas?

Found the problem. Turns out I tried sending the files before the buffer of the writing process was fully flushed.

So, it was a synchronization issue and not an encoding issue.

Sorry about that, and thanks for the help guys!

Could it be related to your current base64.MAXBINSIZE? Encoders.encode_base64 uses base64.encodestring internally. The default value for base64.MAXBINSIZE is 57, can always try setting it larger: base64.MAXBINSIZE = 65536

If the file is already written--be sure to .close() the file and re-open()/.read() it for the payload.

My issues stemmed from timing and this solved the issue for me.