Table of contents

Setup a Local Only SMTP Email Server (Linux, Unix, Mac)
curl
1. with attachment
mailx
Mutt
uuencode and mail
1. Command
Mpack
1. Install Debian/Ubuntu
2. Command
Sendemail.pl
1. Command
Swaks
Telnet
Sending Email with a MIME Boundary
1. Sendmail
Netcat
Install Debian/Ubuntu

Setup a Local Only SMTP Email Server (Linux, Unix, Mac)

curl

curl --url 'smtp://smtp.gmail.com:587' \
     --ssl-reqd \
     --mail-from 'your-email@gmail.com' \
     --mail-rcpt 'recipient-email@example.com' \
     --upload-file mail.txt \
     --user 'your-email@gmail.com:your-email-password' \
     --insecure \
     --verbose

Detailed Explanation of Options

--url 'smtp://smtp.gmail.com:587':
- Specify the SMTP server and port to connect to. Gmail uses smtp.gmail.com on port 587.
--ssl-reqd:
- Enforces SSL/TLS encryption.
--mail-from 'your-email@gmail.com':
- The sender’s email address.
--mail-rcpt 'recipient-email@example.com':
- The recipient’s email address. You can specify multiple recipients by using multiple –mail-rcpt options.
--upload-file mail.txt:
- Specify the file that contains the email’s content. This file should include the email headers and body.
--user 'your-email@gmail.com:your-email-password':
- The SMTP server authentication details in the format username:password.
--insecure:
- Allows connections to SSL sites without certificates. Remove this if you want to enforce certificate validation.
--verbose:
- Provides detailed information about the curl operation.

with attachment

curl --url 'smtp://smtp.gmail.com:587' \
     --ssl-reqd \
     --mail-from 'your-email@gmail.com' \
     --mail-rcpt 'recipient-email@example.com' \
     --user 'your-email@gmail.com:your-email-password' \
     --upload-file mime-email.txt \
     --insecure \
     --verbose

mem-email.txt

  From: your-email@gmail.com
  To: recipient-email@example.com
  Subject: Test Email with Attachment
  MIME-Version: 1.0
  Content-Type: multipart/mixed; boundary="simple boundary"
    
  --simple boundary
  Content-Type: text/plain; charset=us-ascii
    
  This is the body of the email.
    
  --simple boundary
  Content-Type: text/plain; charset=us-ascii
  Content-Disposition: attachment; filename="attachment.txt"
    
  This is the content of the attachment.
    
  --simple boundary--

mailx

Install on Debian/Ubuntu

apt-get install postfix

Alternatively, without the bloat of postfix

apt-get install heirloom-mailx

Install on Redhat/Centos

yum install mailx

Command

    cat mysqldbbackup.sql | mailx backup@email.com

   mailx -a backup.sql -a grants.sql backup@email.com

Newer versions of mailx support -a flag for attachments!

Script Example

   #!/bin/bash
   
   # Email details
   TO="recipient@example.com"
   SUBJECT="Test Email with Attachment"
   FROM="sender@example.com"
   BODY="This is the plain text body of the email"
   HTML_BODY="<html><body><h1>This is the HTML body</h1></body></html>"
   ATTACHMENT="file.txt"
   
   # Send the email
   echo "$BODY" | mailx -a "Content-Type: text/html" -s "$SUBJECT" -a "From: $FROM" $TO -A $ATTACHMENT

Mutt

Install on Debian/Ubuntu

apt-get install mutt

Install on Redhat/Centos

yum install mutt

Command

    echo "This is the message body" | mutt -a "/path/to/file.to.attach" -s "subject of message" -- recipient@example.com

uuencode and mail

This sends the uuencoded part inline and not as an attachment. Many mail-clients recognize this though and display the uuencoded part as an
attachment. Don’t use uuencode when other alternatives use
MIME.

Command

    gzip -c ldiff.sql | uuencode mysqldbbackup.sql.gz  | mail -s "Ldiff from openldap" backup@example.com

Mpack

Install Debian/Ubuntu

apt-get install mpack

Command

    mpack -s subject /dev/stdin loser@example.com < file

Sendemail.pl

http://caspian.dotconf.net/menu/Software/SendEmail/

Command

    sendemail -f mandatory@email.com-t to@some.one -m "Here are your files!" -a file1.jpg file2.zip

Swaks

Install Debian/Ubuntu

Swaks is an smtp of CURL, install it first:

curl http://www.jetmore.org/john/code/swaks/files/swaks-20130209.0/swaks -o swaks

Set the permissions for the script so you can run it

chmod +x swaks

It’s based on perl, so install perl

sudo apt-get -y install perl

apt-get install swaks

Command

    swaks -tls \
    --to ${MAIL_TO} \
    --from ${MAIL_FROM} \
    --server ${MAIL_SERVER} \
    --auth LOGIN \
    --auth-user ${MAIL_USER} \
    --auth-password ${MAIL_PASSWORD} \
    --header "Subject: $MAIL_SUBJECT" \
    --header "Content-Type: text/html; charset=UTF-8" \
    --body "$MESSAGE" \
    --attach mysqldbbackup.sql

Bash Script

Uses HTML file
Uses an inline Image for an HTML file and attachment

Bash Script With Attachments

#!/bin/bash

swaks -f sender@gmail.com --auth \
  --server smtp.sendgrid.net:587 \
  --au apikey \
  --ap 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 \
  --to receiver@gmail.com \
  --header "Content-Type: text/html; charset=UTF-8" \
  --attach-type text/html \
  --attach-body @../EmailTemplate/EmailTemplate.html \
  --h-From: '"bob" <bob@gmail.com>' \
  --h-Subject: "Subject" \
  --add-header "Content-ID: inlineImage.png" \
  --attach-name "inlineImage.png" \
  --attach-type image/png \
  --attach @../EmailTemplate/inlineImage.png

Telnet

First, you need to find out the SMTP server address for the domain. Let’s find out the SMTP server address for gmail.com

Goto MS Dos prompt and type nslookup command.

> set q=mx
> gmail.com

Non-authoritative answer:
gmail.com       MX preference = 30, mail exchanger =     
gmail.com       MX preference = 20, mail exchanger = alt2.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
gmail.com       MX preference = 40, mail exchanger = alt4.gmail-smtp-in.l.google.com

Now connect to gmail SMTP server with Telnet by typing the following command on the command prompt.

telnet alt3.gmail-smtp-in.l.google.com 25

220 mx.google.com ESMTP t15si14936218ibf.58
helo kathir
250 mx.google.com at your service
mail from: <kathirusa@yahoo.com>
250 2.1.0 OK t15si14936218ibf.58
rcpt to: <kathircpp@gmail.com>
250 2.1.5 OK t15si14936218ibf.58
data
354  Go ahead t15si14936218ibf.58
from: kathir
to: kathir
subject: hi from kathir

This is for testing

.
250 2.0.0 OK 1287958967 t15si14936218ibf.58

Sending Email with a MIME Boundary

MIME (Multipurpose Internet Mail Extensions) boundaries

BOUNDARY: This is a unique string that acts as a boundary between different parts of the email content.Each section is separated by
--BOUNDARY,
and
the end of the email is indicated with --BOUNDARY--.
Multipart/alternative: This allows sending both plain text and HTML versions of the email so that the email client can choose which one to
display.
Content-Type: This specifies the type of content in each part. text/plain for plain text and text/html for HTML.
Content-Type: multipart/mixed: This specifies that the email contains multiple parts (like text and attachments).
base64: Converts the file into a base64 string for safe transmission via email.
Content-Disposition: attachment: Marks the part of the email as an attachment.

Sendmail

Example 1

#!/bin/bash

to="any@email.com"
from="your@email.com"
boundary=$(uuidgen -t)
body_boundary=$(uuidgen -t)
now=$(date +"%a, %d %b %Y %T %z")

sendmail -t << EOF2
From: ${from}
To: ${to}
Date: ${now}
Subject: This is a test multipart message
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="${boundary}"

--${boundary}
Content-Type: multipart/alternative; boundary="${body_boundary}"

--${body_boundary}
Content-type: text/plain; charset=ISO-8859-1

This is a text message.     --> Here am going to incorporate text version
--${body_boundary}
Content-type: text/html; charset=utf-8
Content-Disposition: inline

<!DOCTYPE html>
<body>
<pre>
Hello,

This is a html version.     --> here am going to incorporate html version

Regards...
</pre>
<body>
--${body_boundary}--
--${boundary}--
EOF2

sc=$?
echo "sedmail rc=${rc}"

Example With Attachment

#!/bin/bash

# Define email details
TO="recipient@example.com"
SUBJECT="Test Email with Attachment"
FROM="sender@example.com"
ATTACHMENT="file.txt"
FILENAME=$(basename "$ATTACHMENT")

# Define the boundary
BOUNDARY="ZZ_/afg6432dfgkl.94531q"

# Create the email content
{
  echo "From: $FROM"
  echo "To: $TO"
  echo "Subject: $SUBJECT"
  echo "MIME-Version: 1.0"
  echo "Content-Type: multipart/mixed; boundary=\"$BOUNDARY\""
  echo ""
  
  # Plain text version of the email
  echo "--$BOUNDARY"
  echo "Content-Type: text/plain; charset=\"UTF-8\""
  echo "Content-Transfer-Encoding: 7bit"
  echo ""
  echo "This is the plain text version of the email."
  echo ""

  # Attachment part
  echo "--$BOUNDARY"
  echo "Content-Type: application/octet-stream; name=\"$FILENAME\""
  echo "Content-Transfer-Encoding: base64"
  echo "Content-Disposition: attachment; filename=\"$FILENAME\""
  echo ""
  base64 "$ATTACHMENT"
  echo ""

  # End of the multipart message
  echo "--$BOUNDARY--"
} | sendmail -t

Netcat

Install Debian/Ubuntu

    apt-get install netcat

Script for Netcat

    #!/bin/sh

    # Default reception
    TOEMAIL="myEmail@domain.ltd";
    # Default Subject
    SUBJECT="You got mail - $DATE";
    # Default Contents
    MSGBODY="Hello, this is the default message body";
    # Default Attachment
    #ATTACHMENT="/tmp/testoutput"
    # Default smtp server
    mailserver="smtp.server.ltd"
    mailserverPort="25"

    showUsage() {
            echo "$0 -a /file/to/attach [-m /message/file] [-M \"Message string\"] -s \"subject\" -r receiver@domain.com"
            echo
            echo "The attachment (-a) is required, if no attachment is used then rather use sendmail directly."
    }

    fappend() {
        echo "$2">>$1;
    }
    DATE=`date`

    # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
    # This might need correction to work on more places, this is tested at a ubuntu 13.10 machine.  #
    # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
    domain=`grep search /etc/resolv.conf | awk '{print $2;}'`
    computer=`hostname`
    user=`whoami`
    FREMAIL="$user@$computer.$domain"

    while getopts "M:m:a:s:r:" opt; do
      case $opt in
            s)
              SUBJECT="$OPTARG - $DATE"
              ;;
            r)
              TOEMAIL="$OPTARG"
              ;;
            m)
              MSGBODY=`cat $OPTARG`
              ;;
            M)
              MSGBODY="$OPTARG"
              ;;
            a)
              ATTACHMENT="$OPTARG"
              ;;
            :)
              showUsage
              ;;
            \?)
              showUsage
              ;;
      esac
    done

    if [ "$ATTACHMENT" = "" ]; then
            showUsage
            exit 1
    fi

    MIMETYPE=`file --mime-type -b $ATTACHMENT`
    TMP="/tmp/tmpmail_"`date +%N`;
    BOUNDARY=`date +%s|md5sum|awk '{print $1;}'`
    FILENAME=`basename $ATTACHMENT`

    DATA=`cat $ATTACHMENT|base64`

    rm $TMP 2> /dev/null

    fappend $TMP "EHLO $computer.$domain"
    fappend $TMP "MAIL FROM:<$FREMAIL>"
    fappend $TMP "RCPT TO:<$TOEMAIL>"
    fappend $TMP "DATA"
    fappend $TMP "From: $FREMAIL"
    fappend $TMP "To: $TOEMAIL"
    fappend $TMP "Reply-To: $FREMAIL"
    fappend $TMP "Subject: $SUBJECT"
    fappend $TMP "Content-Type: multipart/mixed; boundary=\"$BOUNDARY\""
    fappend $TMP ""
    fappend $TMP "This is a MIME formatted message.  If you see this text it means that your"
    fappend $TMP "email software does not support MIME formatted messages."
    fappend $TMP ""
    fappend $TMP "--$BOUNDARY"
    fappend $TMP "Content-Type: text/plain; charset=UTF-8; format=flowed"
    fappend $TMP "Content-Disposition: inline"
    fappend $TMP ""
    fappend $TMP "$MSGBODY"
    fappend $TMP ""
    fappend $TMP ""
    fappend $TMP "--$BOUNDARY"
    fappend $TMP "Content-Type: $MIMETYPE; name=\"$FILENAME\""
    fappend $TMP "Content-Transfer-Encoding: base64"
    fappend $TMP "Content-Disposition: attachment; filename=\"$FILENAME\";"
    fappend $TMP ""
    fappend $TMP "$DATA"
    fappend $TMP ""
    fappend $TMP ""
    fappend $TMP "--$BOUNDARY--"
    fappend $TMP ""
    fappend $TMP "."
    fappend $TMP "quit"

    netcat $mailserver $mailserverPort < $TMP >> $TMP
    rc="$?"
    if [ "$rc" -ne "0" ]; then
        echo "Returncode: $rc"
        echo "Please inspect $TMP"
    else
        rm $TMP;
    fi