Python mailing script

mailer.py

# Example of mailing script. Quick and (a little) dirty.
# Dih5 - 2017
# Spam is not cool. Thou shalt not spam!

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

# Make sure to active lesser secure apps here:
# https://www.google.com/settings/security/lesssecureapps
 
fromaddr = "myaddress@gmail.com"
mypasswd = "passwordIsExposedInThisFile"
address_file = "ToSend.lst" # Email addresses separated by \n

# Amount of recipients in a single message (sent as BCC)
block = 50
# Max number of messages to send when the script is run
max_msgs = 5

def grouper(iterable, n, fillvalue=None):
    "Collect data into fixed-length chunks or blocks"
    # grouper('ABCDEFG', 3, 'x') --> ABC DEF Gxx"
    args = [iter(iterable)] * n
    return itertools.zip_longest(*args, fillvalue=fillvalue)
 
msg = MIMEMultipart()
 
msg['From'] = fromaddr
#msg['To'] = [fromaddr] # No data in the header, all BCC
msg['Subject'] = "The email subject"
 
body = "This is the text of the email"
 
msg.attach(MIMEText(body, 'plain'))
 
filename = "Sample.pdf"  # Name that will be used to send the file
attachment = open("Sample.pdf", "rb")  # Path to the file
 
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)

with open(address_file, 'r') as f:
    addr_list = f.readlines()
    
addr_list=list(map(lambda s:s.strip(),addr_list))

try:
    i=0
    msgs_sent = 0
    server = smtplib.SMTP('smtp.gmail.com', 587)
    server.starttls()
    server.login(fromaddr, mypasswd)
    
    for to_addr in grouper(addr_list, block):
        if msgs_sent >= max_msgs:
            print("************\nDesired number of messages sent. Aborting further sending.")
            raise Exception("Max messages sent")
        #msg.replace_header('To', to_addr)
        text = msg.as_string()
        server.sendmail(fromaddr, [s for s in to_addr if s is not None], text)
        print(to_addr)
        i+=block
        msgs_sent += 1
        
        
        
except Exception:
    print("************\nProcess failed while sending to " + addr_list[i])
    print(traceback.format_exc())
finally:
    with open(address_file,'w') as f:
        for item in addr_list[i:]:
            f.write("{}\n".format(item))
    print("List of recipients updated")
    
    server.quit()