CODEWITHSUNDEEP
pythonperformanceemailsmtp
s5s
s5s

Reputation: 12144

Python sending email too slow

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 = '[email protected]'
    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('[email protected]',  'hi')

Upvotes: 2

Views: 10937

Answers (4)

Alberto Trentadue
Alberto Trentadue

Reputation: 659

Maybe this comes very late, but I think it is relevant for the matter. I had the same issue recently and realized, by searching around, that the call to connect the SMTP server may be very time consuming due to issues with domain name resolution, since the SMTP server performs a reverse lookup to verify the connecting client.

In my case this call was taking around 1 minute!:

s = smtplib.SMTP(smtp_server)

Solution was to fix the domain name resolution on the Linux box. After that, connection became very quick.

Hope this may be of help.

Upvotes: 2

jfs
jfs

Reputation: 414275

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())

Upvotes: 6

taleinat
taleinat

Reputation: 8701

The real answer here is "profile that code!". Time how long different parts of the code take so you know where most of the time is spent. That way you'll have a real answer without guesswork.

Still, my guess would be that it is the calls to smtp_serv.verify(recipient) may be the slow ones. Reasons might be that the server sometimes needs to ask other SMTP servers for info, or that it does throttling on these operations to avoid having spammers use them massively to gather email addresses.

Also, try pinging the SMTP server. If the ping-pong takes significant time, I would expect sending each email would take at least that long.

Upvotes: 1

Mark Lavin
Mark Lavin

Reputation: 25164

You are opening the connection to the SMTP server and then closing it for each email. It would be more efficient to keep the connection open while sending all of the emails.

Upvotes: 3

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