BCC not hidden on gmail using python smtplib

Question

I am working on a python script to send email to my customer with a survey. I will send only one email with all my customers's emails in the BCC field so that I do not need to loop through all the emails. Everything works fine when I tested sending emails to my company's coleagues and also when I sent to my personal email, but whenever I send to a gmail account, the BCC field appears to not be hidden and show all the emails. I found this post Email Bcc recipients not hidden using Python smtplib and tried that solution as well, but as I am using a html body email, the emails were shown inside the body. Can anyone help me on this one?

import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.mime.image import MIMEImage


def send_survey_mail():

template_path = 'template.html'
background_path = 'image.png'
button_path = 'image2.png'

try:
    body = open(template_path, 'r')
    msg = MIMEMultipart()

    msg['Subject'] = 'Customer Survey'
    msg['To'] = ', '.join(['[email protected]', '[email protected]'])
    msg['From'] = '[email protected]'
    msg['Bcc'] = '[email protected]'

    text = MIMEText(body.read(), 'html')
    msg.attach(text)

    fp = open(background_path, 'rb')
    img = MIMEImage(fp.read())
    fp.close()

    fp2 = open(button_path, 'rb')
    img2 = MIMEImage(fp2.read())
    fp2.close()

    img.add_header('Content-ID', '<image1>')
    msg.attach(img)

    img2.add_header('Content-ID', '<image2>')
    msg.attach(img2)

    s = smtplib.SMTP('smtpserver')

    s.sendmail('[email protected]',
               ['[email protected]', '[email protected]', '[email protected]'],
               msg.as_string())
    s.quit()
except Exception as ex:
    raise ex

send_survey_mail()

I removed the following line from the code and tried again. Now the email is not sent to my customer's Gmail email.

msg['Bcc'] = '[email protected]'

Answer 1

Just do not mention bcc mails in msg['To'] or msg['Cc']. Do it only in server.sendmail()

import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.mime.base import MIMEBase
from email import encoders

from_addr = "[email protected]"
to_addr = ["[email protected]", "[email protected]"]

msg = MIMEMultipart()

msg['From'] = from_addr
msg['To'] = to_addr
msg['Subject'] = "SUBJECT"

body = "BODY"

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

filename = "FILE.pdf"
attachment = open('/home/FILE.pdf', "rb")

part = MIMEBase('application', 'octet-stream')
part.set_payload((attachment).read())
encoders.encode_base64(part)
part.add_header('Content-Disposition', "attachment; filename= %s" % filename)

msg.attach(part)

server = smtplib.SMTP('.....', 587)
server.starttls()
server.login(from_addr, 'yourpass')
text = msg.as_string()
server.sendmail(from_addr, to_addr + [[email protected]], text)
server.quit()

Answer 2

Did you try not to define the msg['BCC'] field? Setting this field forces it to be included. It is sufficient that the BCC email address is in the sendmail command's destination address list. Take a look at this question.

Answer 3

MAIL_FROM = [email protected]
MAIL_DL = [email protected]

def send(to, cc, bcc, subject, text, html):
    message = MIMEMultipart("alternative")
    message["Subject"] = subject
    message["From"] = MAIL_FROM
    message["To"] = to
    message["Cc"] = cc + "," + MAIL_DL

    if html is not None:
        body = MIMEText(html, "html")
    else:
        body = MIMEText(text)
    message.attach(body)

    server = smtplib.SMTP(MAIL_SERVER)
    server.set_debuglevel(1)

    server.sendmail(MAIL_DL, to.split(",") + bcc.split(","), message.as_string())
    server.quit()

    return {
        "to": to,
        "cc": cc,
        "bcc": bcc,
        "subject": subject,
        "text": text,
        "html": html,
    }