Develop Reference

Sending mail with python SMTP to outlook/microsoft gives SMTPAuthenticationError: Authentication unsuccessful

I have a problem described and solved for gmail in this post. I have read through several posts dealing with similar issues (Sending mail from Python using SMTP, Sending email from Python using STARTTLS, smtplib.SMTPAuthenticationError: (535, '5.7.3 Authentication unsuccessful')) and also some external support on Microsoft (eg. send email using Microsoft 365 but in none I was able to figure out how to fix my error.
My code is this:
import getpass
import smtplib
mailserver = smtplib.SMTP('smtp.office365.com',587)
mailserver.ehlo()
mailserver.starttls()
a = getpass.getpass('Password: ')
mailserver.login('name#domain.com', a)
and connection is established (ie. I get 250 for .ehlo and 220 for .starttls) but the last step gives me:
SMTPAuthenticationError: (535, b'5.7.3 Authentication unsuccessful [LO4P123CA0352.GBRP123.PROD.OUTLOOK.COM]')
The documentation says:
SMTP authentication went wrong. Most probably the server didn’t accept the username/password combination provided.
I am sure that my password and username are correct (triple checked that). Also, I looked to my account and in the Microsoft account it shows that POP and IMAP are allowed and it gives me:
Server name: smtp.office365.com
Port: 587
Encryption method: STARTTLS
so everything should be ok. I have also tried port 25 which gives the same error. Where is the problem? How can I make it work for Outlook/Microsoft 365? Thanks for any help.

Python smtplib hangs when sendmessage() is called

I'm trying to send a message from a gmail account using smtplib. I've been messing with it in the shell, and everything works fine until I call sendmail(), when it just freezes until I close the terminal. No errors, just freezing. My commands look like this:
>>> import smtplib
>>> connection = smtplib.SMTP("smtp.gmail.com", 587)
>>> connection.ehlo()
>>> connection.starttls()
>>> connection.login("gmail_id", "gmail_pwd")
>>> connection.sendmail("addr_from", "addr_to", "message")
Has anybody had this problem? I've tried pinging smtp.gmail.com and using telnet smtp.gmail.com 587, and they both connect.

Use connection.set_debuglevel(1) to enable tracking/debugging SMTP session.
https://docs.python.org/2/library/smtplib.html#smtplib.SMTP.set_debuglevel

I had a similar issue just now, I had tried to login to my gmail account using python3.7's smtplib and was getting:
smtplib.SMTPAuthenticationError: (535, b'5.7.8 Username and Password not accepted. Learn more at\n5.7.8 https://support.google.com/mail/?p=BadCredentials')
I went to my gmail inbox using a browser, saw that I received a security alert email with the message
Less secure app blocked: Google blocked the app you were trying to use
because it doesn't meet our security standards.Some apps and devices
use less secure sign-in technology, which makes your account more
vulnerable. You can turn off access for these apps, which we
recommend, or turn on access if you want to use them despite the
risks. Google will automatically turn this setting OFF if it's not
being used.
After I followed the instructions in the aforementioned email and enabled less secure apps access on my gmail account, I tried sendmail still using the initial SMTP connection, but it just hung with no output.
I then proceeded to quit the initial SMTP connection and created a new one (post less secure apps enabled) like below and it worked!
conn = smtplib.SMTP('smtp.gmail.com', 587)

Sending an email, via python, from one outlook account to another

I'm writing a program to help the school's Biology Department and it involves sending an email. I've gathered all of the variables I need for the content of the message, it's just the actual sending of the email that's causing some issues.
I've looked around and realized that I was using code that sent to gmail, whereas the servers at school use Outlook 2010. Once I remembered that, I looked around for some python code that sent emails, but so far nothing has worked.
It all seems very complicated for just sending an email, but I need some help as to were to go from here.
gsal.org.uk is our school's web server address, which is an outlook server.
The current error that I am receiving is smtplib.SMTPException: STARTTLS extension not supported by server., but I keep receiving various errors with everything I try.
This is the code:
fromaddr = "test#gsal.org.uk"
toaddrs = "technicians#gsal.org.uk"
msg = "\r\n".join([
"From: user",
"To: user",
"Subject: Practical Request",
"",
"Test"
])
server = smtplib.SMTP_SSL('smtp.gmail.com:465')
server.ehlo()
server.starttls()
# server.login(username,password)
server.sendmail(fromaddr, toaddrs, msg)
server.quit()
messagebox.showinfo("Success!", "Your request has been sent successfully.")
All I want to do is send an email from an email account (specified within the program) to an email account that will soon be set up at school called technicians#gsal.org.uk. Any help appreciated.
EDIT
Thought I'd add the fact that if I remove the starttls() line, I get this:
smtplib.SMTPSenderRefused: (530, b'5.5.1 Authentication Required. Learn more at\n5.5.1 https://support.google.com/mail/answer/14257 hw1sm42144009wjb.6 - gsmtp', 'test#gsal.org.uk')
I've read that link, but it seems to be talking about gmail? I want to use outlook? I understand that I need to do authentication, but how?

In order to fight spam and protect resources, a normally configured SMTP server provides its services only to its owner (e.g. a company, organization or registered customers). Your school server probably accepts mail only if it is:
addressed to the school's own domain, or
coming from an authenticated person (e.g. a student, teacher), or
coming from a host with IP address belonging to the school's LAN (when allowed by the admin)
Further, a SMTP server communicates with other servers on TCP port 25 and with users submitting new mail (which is your case) on port 465 or 587. (Port 25 was used in the past for all mail, this is now deprecated)
Communication on port 465 is always encrypted (TLS). Communication on port 587 starts in plaintext, but with the STARTTLS command, the encryption is turned on. A successfull STARTTLS is usually required to allow authentication (login).
Why your progam does not work?
You are trying to start TLS on an TLS connection. It has been started. Either don't STARTTLS or change the port to 587.
You are using gmail's server to send a message not addressed to gmail. In this case you must login with a name and a password as a registered gmail user.
What should help? Contact the local admin for details about using the school's own server.

Python 2: SMTPServerDisconnected: Connection unexpectedly closed

I have a small problem with sending an email in Python:
#me == my email address
#you == recipient's email address
me = "some.email#gmail.com"
you = "some_email2#gmail.com"
# Create message container - the correct MIME type is multipart/alternative.
msg = MIMEMultipart('alternative')
msg['Subject'] = "Alert"
msg['From'] = me
msg['To'] = you
# Create the body of the message (a plain-text and an HTML version).
html = '<html><body><p>Hi, I have the following alerts for you!</p></body></html>'
# Record the MIME types of both parts - text/plain and text/html.
part2 = MIMEText(html, 'html')
# Attach parts into message container.
# According to RFC 2046, the last part of a multipart message, in this case
# the HTML message, is best and preferred.
msg.attach(part2)
# Send the message via local SMTP server.
s = smtplib.SMTP('aspmx.l.google.com')
# sendmail function takes 3 arguments: sender's address, recipient's address
# and message to send - here it is sent as one string.
s.sendmail(me, you, msg.as_string())
s.quit()
So before now, my program didn't give me an error, but it also didn't send me an email. And now python gives me an error:
SMTPServerDisconnected: Connection unexpectedly closed
How can I fix this?

TLDR: switch to authenticated connection over TLS.
Most probably the gmail server rejected the connection after the data command (very nasty of them to do so at this stage :). The actual message is most probably this one:
retcode (421); Msg: 4.7.0 [ip.octets.listed.here 15] Our system has detected an unusual rate of
4.7.0 unsolicited mail originating from your IP address. To protect our
4.7.0 users from spam, mail sent from your IP address has been temporarily
4.7.0 rate limited. Please visit
4.7.0 https://support.google.com/mail/answer/81126 to review our Bulk Email
4.7.0 Senders Guidelines. qa9si9093954wjc.138 - gsmtp
How do I know that? Because I've tried it :) with the s.set_debuglevel(1), which prints the SMTP conversation and you can see firsthand what's the issue.
You've got two options here:
Continue using that relay; as explained by Google, it's unencrypted gmail-to-gmail only, and you have to un-blacklist your ip through their procedure
The most fool-proof option is to switch to TLS with authentication
Here's how the changed source looks like:
# skipped your comments for readability
import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
me = "some.email#gmail.com"
my_password = r"your_actual_password"
you = "some.email2#gmail.com"
msg = MIMEMultipart('alternative')
msg['Subject'] = "Alert"
msg['From'] = me
msg['To'] = you
html = '<html><body><p>Hi, I have the following alerts for you!</p></body></html>'
part2 = MIMEText(html, 'html')
msg.attach(part2)
# Send the message via gmail's regular server, over SSL - passwords are being sent, afterall
s = smtplib.SMTP_SSL('smtp.gmail.com')
# uncomment if interested in the actual smtp conversation
# s.set_debuglevel(1)
# do the smtp auth; sends ehlo if it hasn't been sent already
s.login(me, my_password)
s.sendmail(me, you, msg.as_string())
s.quit()
Now, if try to 'cheat' the system and send with a different (non-gmail) address it's gonna a) require you to connect to a different hostname (some of the MX records for gmail), then b) stop you and close the connection on the grounds of blacklisted ip, and c) do reverse DNS, DKIM and lots of other countermeasures to make sure you're actually in control of the domain you presented in the MAIL FROM: address.
Finally, there's also option 3) - use any other email relaying service, there are tons of good ones :)

I Had the same issue and solved it just by specifying the right port like this:
smtplib.SMTP('smtp.gmail.com', 587)

Using smtplib.SMTP_SSL() instead of smtplib.SMTP() works for me. Try this.

I have realised a strange behavior. I have used similar codes mentioned both the question and answers. My code has been working for the last days. However, today I encountered the error message mentioned in the question.
My solution:
I had tried my successful attempt via library network. Today I have tried it via Starbucks network (over captive portal). I changed it to my mobile network. It started working again.
Possibly, Google rejects requests from unreliable networks.

I was facing the same problem. In my case, password was changed just few days back. So, it was giving the error. As I updated the password in code, its working like a charm...!!!

Googlers: I had a test smtp server running locally. I was getting this error because I was shutting down the local smtp server before closing the client smtp.

with smtplib.SMTP_SSL("smtp.mail.yahoo.com", port=465) as connection:
connection.login(
user=my_email,
password=my_password
)
connection.sendmail(
from_addr=my_email,
to_addrs=friend_address,
msg=f"Subject:Text\n\n"
f"Body of the text"
)
This is my code. I hope it will be helpful.

SMTP directly to a host's MX record

I've tried playing around in python to learn more about the smtp protocol. More precisely I'm been trying to send a mail straight to a host's smtp server, but with little success.
For example, say I want to send a mail to a gmail.com address, I lookup the mx record for gmail.com:
>> nslookup -type=MX gmail.com
gmail.com MX preference = 40, mail exchanger = alt4.gmail-smtp-in.l.google.com
gmail.com MX preference = 5, mail exchanger = gmail-smtp-in.l.google.com
gmail.com MX preference = 10, mail exchanger = alt1.gmail-smtp-in.l.google.com
Then I do the following in python:
import smtplib
# Tried both port 465 and 587 (can't test port 25 since it's blocked by my ISP)
s = smtplib.SMTP("alt1.gmail-smtp-in.l.google.com", 587)
I tried several, and for everyone but one I always got a:
"[Errno 10051] A socket operation was attempted to an unreachable network" or
"[Errno 10060] A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because conneted host has failed to respond" exception.
I read somewhere that some mail servers do a reverse lookup on your IP, and rejecting the connection if it hasn't got a domain. How do they do that?
I also read somewhere that many mail servers reject incoming mails from dynamic IP addresses (which I obviously have as a private customer to my ISP). How can they check if an IP address is dynamic or static?
Are these the reasons most servers seem to reject my connection? Or is there something more to it?

Um, your problem is exactly this:
# Tried both port 465 and 587 (can't test port 25 since it's blocked by my ISP)
Google's MX server is listening on port 25. If your ISP does not allow outgoing connections on this port, then you will not be able to send SMTP messages the way you are trying to do. You should get this sorted out with your ISP.
Regarding the rejection of messages, sending e-mail directly like this does increase the likelihood that it will be rejected or flagged as spam. Particularly if you set the "from" address to something that does not match the domain associated with your IP address, or if your SMTP client sends a mismatched domain in its EHLO message, or if the content of your message looks "spammy". The actual behavior will vary according to how each individual MX server has been configured.

Direct to MX email like you describe above will be blocked by Gmail's SMTP servers, with an error message "421-4.7.0", however many other SMTP severs, like MailEnable will allow Direct To MX.
The following website has source code for .NET and PHP for Direct to MX code, http://www.directtomx.com - you may be able to consume the webservice in python using SUDS.