smtplib not honoring bcc header #75235

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1. zoof commented on Jul 26, 2017

   

   zoofmannequin

   on Jul 26, 2017

   MannequinAuthor

   More actions

   When I try sending an email, using smtplib, with the bcc header set, the bcc header is included in messages send to the "to" and "cc" addresses. According to section 4.5.3 of rfc 822:

   > The contents of this field are not included in copies of the message sent to the primary and secondary  recipients.
   

   So this behavior is incorrect. It should not be up to the mail client to ignore the bcc field.

   Here's a script that can replicate the problem:

   #!/usr/bin/env python

   import smtplib
   from email.MIMEMultipart import MIMEMultipart
   from email.MIMEText import MIMEText
   
   body = "this is a test"
   
   #craft the message
   fromaddr = 'ned@example.com'
   server = smtplib.SMTP('smtp.example.com', 587)
   p = 'Hunter2!'
   subject = "test"
   toaddr = "foo@example.com"
   ccaddr = "bar@example.com"
   bccaddr = "baz@example.com"
   
   msg = MIMEMultipart()

   msg['cc'] = ccaddr
   msg['bcc'] = bccaddr
   msg['From'] = fromaddr
   msg['To'] = toaddr
   msg['Subject'] = subject

   msg.attach(MIMEText(body, 'plain'))

   #send the message
   server.starttls()
   server.login(fromaddr, p)
   text = msg.as_string()
   server.sendmail(fromaddr, toaddr, text)
   server.quit()
2. zoof

   added

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Jul 26, 2017
3. bitdancer commented on Jul 27, 2017

   

   bitdancer

   on Jul 27, 2017

   Member

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   smtplib in 2.7 doesn't know anything about RFC822 or any of the replacement RFCs. sendmail accepts a *string*, and doesn't understand or modify anything about that string except the newlines. It is your responsibility not to *add* the BCC header. What you want to do is put the BCC (and CC!) recipients in your toaddr list passed to sendmail, and *not* add a BCC header.

   In Python3 smtplib has a send_message method that accepts a Message object, and that method uses the BCC to inform where to send the message and strips the header before sending. That is, smtplib's send_message method *does* implement RFC5322 behaviors.
4. bitdancer

   closed this as completedon Jul 27, 2017
5. bitdancer

   added

   invalid

   on Jul 27, 2017
6. ezio-melotti

   transferred this issue fromon Apr 10, 2022