Question

I have the script below which I’m using to send say 10 messages myself<->myself. However, I’ve noticed that Python really takes a while to do that. Last year I needed a system to send about 200 emails with attachments and text and I implemented it with msmtp + bash. As far as I remember it was much faster.

Moving the while loop inside (around the smtp_serv.sendmail(sender, recepient, msg) function yields similar results).

Am I doing something wrong? Surely it can’t be slower than bash + msmtp (and I’m only sending a ‘hi’ message, no attachments).

#! /usr/bin/python3.1

def sendmail(recepient,  msg):

    import smtplib

    # Parameters
    sender = '[e-mail]'
    password = 'password'
    smtpStr = 'smtp.gmail.com'
    smtpPort = 587
    # /Parameters

    smtp_serv = smtplib.SMTP(smtpStr, smtpPort)
    smtp_serv.ehlo_or_helo_if_needed()
    smtp_serv.starttls()
    smtp_serv.ehlo()

    recepientExists = smtp_serv.verify(recepient)
    if recepientExists[0] == 250:
        smtp_serv.login(sender, password)
        try:
            smtp_serv.sendmail(sender, recepient, msg)
        except smtplib.SMTPException:
            print(recepientExists[1])
    else:
        print('Error',   recepientExists[0], ':',  recepientExists[1])

    smtp_serv.quit()

for in in range(10):
    sendmail('[e-mail]',  'hi')

Answer 1

In this script it takes five times more time to setup SMTP connection (5 seconds) than to send a e-mail (1 second) so it could make sense to setup a single connection and send several e-mails instead of creating the connection each time:

#!/usr/bin/env python3
import smtplib    
from contextlib import contextmanager
from datetime   import datetime
from email.mime.text import MIMEText
from netrc      import netrc
from timeit     import default_timer as timer

@contextmanager
def logined(sender, password, smtp_host='smtp.gmail.com', smtp_port=587):
    start = timer(); smtp_serv = smtplib.SMTP(smtp_host, smtp_port, timeout=10)
    try: # make smtp server and login
        smtp_serv.ehlo_or_helo_if_needed()
        smtp_serv.starttls()
        smtp_serv.ehlo()
        print('smtp setup took (%.2f seconds passed)' % (timer()-start,))
        start = timer(); smtp_serv.login(sender, password)
        print('login took %.2f seconds' % (timer()-start,))
        start = timer(); yield smtp_serv
    finally:
        print('Operations with smtp_serv took %.2f seconds' % (timer()-start,))
        start = timer(); smtp_serv.quit()
        print('Quiting took %.2f seconds' % (timer()-start,))

smtp_host = 'smtp.gmail.com'
login, _, password = netrc().authenticators(smtp_host)
with logined(login, password, smtp_host) as smtp_serv:
    for i in range(10):
        msg = MIMEText('#%d timestamp %s' % (i, datetime.utcnow()))
        msg['Subject'] = 'test #%d' % i
        msg['From'] = login
        msg['To'] = login
        smtp_serv.send_message(msg) 

Output

smtp setup took (5.43 seconds passed)
login took 0.40 seconds
Operations with smtp_serv took 9.84 seconds
Quiting took 0.05 seconds

If your Python version doesn’t have .send_message() then you could use:

smtp_serv.sendmail(from, to, msg.as_string())