/usr/sbin/sendmail -t — Sending Email with File Attachment (Script Example)

#!/bin/bash

# Variables
TO="recipient@example.com"
SUBJECT="Email with Attachment"
BODY="Hello,\n\nPlease find the attached file.\n\nBest regards,\nYour Script"
ATTACHMENT="example.txt" # Path to the file you want to attach

# Create a unique boundary string
BOUNDARY="====MULTIPART_BOUNDARY_$(date +%s)===="

# Create the email headers
{
    echo "To: $TO"
    echo "Subject: $SUBJECT"
    echo "MIME-Version: 1.0"
    echo "Content-Type: multipart/mixed; boundary=\"$BOUNDARY\""
    echo
    echo "This is a multi-part message in MIME format."
    echo
    # Add the email body
    echo "--$BOUNDARY"
    echo "Content-Type: text/plain; charset=\"utf-8\""
    echo "Content-Transfer-Encoding: 7bit"
    echo
    echo -e "$BODY"
    echo
    # Add the attachment
    echo "--$BOUNDARY"
    echo "Content-Type: $(file --mime-type -b "$ATTACHMENT")"
    echo "Content-Transfer-Encoding: base64"
    echo "Content-Disposition: attachment; filename=\"$(basename "$ATTACHMENT")\""
    echo
    base64 "$ATTACHMENT"
    echo
    # End the email
    echo "--$BOUNDARY--"
} | /usr/sbin/sendmail -t

echo "This is the content of the file." > example.txt

chmod +x send_email_with_attachment.sh

./send_email_with_attachment.sh