How to send email using simple SMTP commands via Gmail

Question

For educational purposes  I need to send an email through an SMTP server  using SMTP s fundamental and simple rules    I was able to do that using smtp4dev  I telnet localhost 25 and and commands are     I want to do the same thing  using Gmail SMTP server  However  it requires authentication and TLS  I can t figure out how to do that for Gmail  Here s a screenshot of telnet smtp gmail com 587     I searched and found many links including Wikipedia s article about STARTTLS command  But I m not able to use TLS and authenticate to Gmail s SMTP server using command line  or sending commands myself in programming languages   Can anyone help

User · Answer

Unfortunately as I am forced to use a windows server I have been unable to get openssl working in the way the above answer suggests.

However I was able to get a similar program called stunnel (which can be downloaded from here) to work. I got the idea from www.tech-and-dev.com but I had to change the instructions slightly. Here is what I did:

Install telnet client on the windows box.
Download stunnel. (I downloaded and installed a file called stunnel-4.56-installer.exe).
Once installed you then needed to locate the stunnel.conf config file, which in my case I installed to C:\Program Files (x86)\stunnel
Then, you need to open this file in a text viewer such as notepad. Look for [gmail-smtp] and remove the semicolon on the client line below (in the stunnel.conf file, every line that starts with a semicolon is a comment). You should end up with something like:
```
[gmail-smtp]
client = yes
accept = 127.0.0.1:25
connect = smtp.gmail.com:465
```
Once you have done this save the stunnel.conf file and reload the config (to do this use the stunnel GUI program, and click on configuration=>Reload).

Now you should be ready to send email in the windows telnet client!
Go to Start=>run=>cmd.

Once cmd is open type in the following and press Enter:

telnet localhost 25

You should then see something similar to the following:

220 mx.google.com ESMTP f14sm1400408wbe.2

You will then need to reply by typing the following and pressing enter:

helo google

This should give you the following response:

250 mx.google.com at your service

If you get this you then need to type the following and press enter:

ehlo google

This should then give you the following response:

250-mx.google.com at your service, [212.28.228.49]
250-SIZE 35651584
250-8BITMIME
250-AUTH LOGIN PLAIN XOAUTH
250 ENHANCEDSTATUSCODES

Now you should be ready to authenticate with your Gmail details. To do this type the following and press enter:

AUTH LOGIN

This should then give you the following response:

334 VXNlcm5hbWU6

This means that we are ready to authenticate by using our gmail address and password.

However since this is an encrypted session, we're going to have to send the email and password encoded in base64. To encode your email and password, you can use a converter program or an online website to encode it (for example base64 or search on google for ’base64 online encoding’). I reccomend you do not touch the cmd/telnet session again until you have done this.

For example [email protected] would become dGVzdEBnbWFpbC5jb20= and password would become cGFzc3dvcmQ=

Once you have done this copy and paste your converted base64 username into the cmd/telnet session and press enter. This should give you following response:

334 UGFzc3dvcmQ6

Now copy and paste your converted base64 password into the cmd/telnet session and press enter. This should give you following response if both login credentials are correct:

235 2.7.0 Accepted

You should now enter the sender email (should be the same as the username) in the following format and press enter:

MAIL FROM:<[email protected]>

This should give you the following response:

250 2.1.0 OK x23sm1104292weq.10

You can now enter the recipient email address in a similar format and press enter:

RCPT TO:<[email protected]>

This should give you the following response:

250 2.1.5 OK x23sm1104292weq.10

Now you will need to type the following and press enter:

DATA

Which should give you the following response:

354  Go ahead x23sm1104292weq.10

Now we can start to compose the message! To do this enter your message in the following format (Tip: do this in notepad and copy the entire message into the cmd/telnet session):

From: Test <[email protected]>
To: Me <[email protected]>
Subject: Testing email from telnet
This is the body

Adding more lines to the body message.

When you have finished the email enter a dot:

This should give you the following response:

250 2.0.0 OK 1288307376 x23sm1104292weq.10

And now you need to end your session by typing the following and pressing enter:

QUIT

This should give you the following response:

221 2.0.0 closing connection x23sm1104292weq.10
Connection to host lost.

And your email should now be in the recipient’s mailbox!

User · Answer

to send over gmail  you need to use an encrypted connection  this is not possible with telnet alone  but you can use tools like openssl  either connect using the starttls option in openssl to convert the plain connection to encrypted     openssl s client -starttls smtp -connect smtp gmail com 587 -crlf -ign eof  or connect to a ssl sockect directly     openssl s client -connect smtp gmail com 465 -crlf -ign eof  EHLO localhost  after that  authenticate to the server using the base64 encoded username password  AUTH PLAIN AG15ZW1haWxAZ21haWwuY29tAG15cGFzc3dvcmQ   to get this from the commandline   echo -ne   00user gmail com 00password    base64 AHVzZXJAZ21haWwuY29tAHBhc3N3b3Jk   then continue with  mail from   like in your example  example session   openssl s client -connect smtp gmail com 465 -crlf -ign eof      lots of openssl output      220 mx google com ESMTP m46sm11546481eeh 9 EHLO localhost 250-mx google com at your service   1 2 3 4  250-SIZE 35882577 250-8BITMIME 250-AUTH LOGIN PLAIN XOAUTH 250 ENHANCEDSTATUSCODES AUTH PLAIN AG5pY2UudHJ5QGdtYWlsLmNvbQBub2l0c25vdG15cGFzc3dvcmQ  235 2 7 0 Accepted MAIL FROM   lt gryphius-demo gmail com gt  250 2 1 0 OK m46sm11546481eeh 9 rcpt to   lt somepoorguy example com gt  250 2 1 5 OK m46sm11546481eeh 9 DATA 354  Go ahead m46sm11546481eeh 9 Subject  it works  yay    250 2 0 0 OK 1339757532 m46sm11546481eeh 9 quit 221 2 0 0 closing connection m46sm11546481eeh 9 read errno 0

User · Answer

Based on the existing answers  here s a step-by-step guide to sending automated e-mails over SMTP  using a GMail account  from the command line  without disclosing the password   Requirements  First  install the following software packages    Expect OpenSSL Core Utils  base64    These instructions assume a Linux operating system  but should be reasonably easy to port to Windows  via Cygwin or native equivalents   or other operating system   Authentication  Save the following shell script as authentication sh      bin bash    Asks for a username and password  then spits out the encoded value for   use with authentication against SMTP servers   echo -n  Email  shown     read email echo -n  Password  hidden     read -s password echo  TEXT   0 email 0 password   echo -ne  TEXT   base64   Make it executable and run it as follows   chmod  x authentication sh   authentication sh   When prompted  provide your e-mail address and password  This will look something like   Email  shown   bob gmail com Password  hidden    AGJvYkBnbWFpbC5jb20AYm9iaXN0aGViZXN0cGVyc29uZXZlcg     Copy the last line  AGJ        as this will be used for authentication   Notification  Save the following expect script as notify sh  note the first line refers to the expect program       usr bin expect  set address   lindex  argv 0   set subject   lindex  argv 1   set ts date   lindex  argv 2   set ts time   lindex  argv 3    set timeout 10 spawn openssl s client -connect smtp gmail com 465 -crlf -ign eof   expect  220      send  EHLO localhost n     expect  250        send  AUTH PLAIN YOUR AUTHENTICATION CODE n       expect  235          send  MAIL FROM   lt YOUR EMAIL ADDRESS gt  n         expect  250            send  RCPT TO   lt  address gt  n           expect  250              send  DATA n             expect  354                send  Subject   subject n n              send  Email sent on  ts date at  ts time  n              send   n  n               expect  250                    send  quit n                                                            Make the following changes    Paste over YOUR AUTHENTICATION CODE with the authentication code generated by the authentication script  Change YOUR EMAIL ADDRESS with the e-mail address used to generate the authentication code  Save the file    For example  note the angle brackets are retained for the e-mail address    send  AUTH PLAIN AGJvYkBnbWFpbC5jb20AYm9iaXN0aGViZXN0cGVyc29uZXZlcg   n  send  MAIL FROM   lt bob gmail com gt  n    Lastly  make the notify script executable as follows   chmod  x notify sh   Send E-mail  Send an e-mail from the command line as follows     notify sh recipient domain com  Command Line   March 14   15 52

User · Answer

As no one has mentioned - I would suggest to use great tool for such purpose - swaks    yum info swaks Installed Packages Name          swaks Arch          noarch Version       20130209 0 Release       3 el6 Size          287 k Repo          installed From repo     epel Summary       Command-line SMTP transaction tester URL           http   www jetmore org john code swaks License       GPLv2  Description   Swiss Army Knife SMTP  A command line SMTP tester  Swaks can test               various aspects of your SMTP server  including TLS and AUTH    It has a lot of options and can do almost everything you want   GMAIL  STARTTLS  SSLv3  and yes  in 2016 gmail still support sslv3     echo  Hello world    swaks -4 --server smtp gmail com 587 --from user gmail com --to user example net -tls --tls-protocol sslv3 --auth PLAIN --auth-user user gmail com --auth-password 7654321 --h-Subject  Test message  --body -     Trying smtp gmail com 587        Connected to smtp gmail com   lt -  220 smtp gmail com ESMTP h8sm76342lbd 48 - gsmtp  - gt  EHLO www example net  lt -  250-smtp gmail com at your service   193 243 156 26   lt -  250-SIZE 35882577  lt -  250-8BITMIME  lt -  250-STARTTLS  lt -  250-ENHANCEDSTATUSCODES  lt -  250-PIPELINING  lt -  250-CHUNKING  lt -  250 SMTPUTF8  - gt  STARTTLS  lt -  220 2 0 0 Ready to start TLS     TLS started with cipher SSLv3 RC4-SHA 128     TLS no local certificate set     TLS peer DN   C US ST California L Mountain View O Google Inc CN smtp gmail com     gt  EHLO www example net  lt    250-smtp gmail com at your service   193 243 156 26   lt    250-SIZE 35882577  lt    250-8BITMIME  lt    250-AUTH LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH  lt    250-ENHANCEDSTATUSCODES  lt    250-PIPELINING  lt    250-CHUNKING  lt    250 SMTPUTF8    gt  AUTH PLAIN AGFhQxsZXguaGhMGdATGV4X2hoYtYWlsLmNvbQBS9TU1MjQ   lt    235 2 7 0 Accepted    gt  MAIL FROM  lt user gmail com gt   lt    250 2 1 0 OK h8sm76342lbd 48 - gsmtp    gt  RCPT TO  lt user example net gt   lt    250 2 1 5 OK h8sm76342lbd 48 - gsmtp    gt  DATA  lt    354  Go ahead h8sm76342lbd 48 - gsmtp    gt  Date  Wed  17 Feb 2016 09 49 03  0000    gt  To  user example net    gt  From  user gmail com    gt  Subject  Test message    gt  X-Mailer  swaks v20130209 0 jetmore org john code swaks     gt     gt  Hello world    gt     gt     gt     lt    250 2 0 0 OK 1455702544 h8sm76342lbd 48 - gsmtp    gt  QUIT  lt    221 2 0 0 closing connection h8sm76342lbd 48 - gsmtp     Connection closed with remote host    YAHOO  TLS aka SMTPS  tlsv1 2    echo  Hello world    swaks -4 --server smtp mail yahoo com 465 --from user yahoo com --to user gmail com --tlsc --tls-protocol tlsv1 2 --auth PLAIN --auth-user user yahoo com --auth-password 7654321 --h-Subject  Test message  --body -     Trying smtp mail yahoo com 465        Connected to smtp mail yahoo com      TLS started with cipher TLSv1 2 ECDHE-RSA-AES128-GCM-SHA256 128     TLS no local certificate set     TLS peer DN   C US ST California L Sunnyvale O Yahoo Inc  OU Information Technology CN smtp mail yahoo com   lt    220 smtp mail yahoo com ESMTP ready    gt  EHLO www example net  lt    250-smtp mail yahoo com  lt    250-PIPELINING  lt    250-SIZE 41697280  lt    250-8 BITMIME  lt    250 AUTH PLAIN LOGIN XOAUTH2 XYMCOOKIE    gt  AUTH PLAIN AGFhQxsZXguaGhMGdATGV4X2hoYtYWlsLmNvbQBS9TU1MjQ   lt    235 2 0 0 OK    gt  MAIL FROM  lt user yahoo com gt   lt    250 OK   completed    gt  RCPT TO  lt user gmail com gt   lt    250 OK   completed    gt  DATA  lt    354 Start Mail  End with CRLF CRLF    gt  Date  Wed  17 Feb 2016 10 08 28  0000    gt  To  user gmail com    gt  From  user yahoo com    gt  Subject  Test message    gt  X-Mailer  swaks v20130209 0 jetmore org john code swaks     gt     gt  Hello world    gt     gt     gt     lt    250 OK   completed    gt  QUIT  lt    221 Service Closing transmission     Connection closed with remote host    I have been using swaks to send email notifications from nagios via gmail for last 5 years without any problem

[email] How to send email using simple SMTP commands via Gmail?

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