Bash SMTP(/S) authentication and mailsending script

send_mail.sh

#!/bin/bash

smtp_address=""
smtp_username=""
smtp_password=""
smtp_server=""
smtp_port=587
use_starttls=true

send_mail() {
    email_recipient="$1"
    email_body="$2"
    email_subject="$3"
    {                                                                          \
    sleep 1;                                                                   \
    printf "HELO %s\n" "$smtp_server";                                         \
    sleep 1;                                                                   \
    printf "AUTH LOGIN\n";                                                     \
    sleep 1;                                                                   \
    printf "%s" "$smtp_username" | base64 -w 0;                                \
    printf "\n";                                                               \
    sleep 1;                                                                   \
    printf "%s" "$smtp_password" | base64 -w 0;                                \
    printf "\n";                                                               \
    sleep 1;
    printf "MAIL FROM: <%s>\n" "$smtp_address";                                \
    sleep 1;                                                                   \
    printf "RCPT TO: <%s>\n" "$email_recipient";                               \
    sleep 1;                                                                   \
    printf "DATA\n";                                                           \
    sleep 1;                                                                   \
    printf "Subject: %s\n" "$email_subject";                                   \
    printf "%s\n" "$email_body";                                               \
    sleep 1;                                                                   \
    printf "\n.\n";
    sleep 1;                                                                   \
    printf "QUIT\n";                                                           \
    } |                                                                        \
    if ${use_starttls} ; then
        openssl s_client -starttls smtp -connect "${smtp_server}:${smtp_port}" \
        -quiet
    else
        telnet "$smtp_server" "$smtp_port"
    fi
}

# example usages:

# unmounted disk notify
disk_mountpoint=""
if ! grep -qs "$disk_mountpoint" /proc/mounts; then
    send_mail "[email protected]" "Unmounted Drive"                       \
    "Unmounted drive detected."
fi

# server down notify
server_address=""
server_port=22
if ! torify nc -z "$server_address" "$server_port" > /dev/null; then
    send_mail "[email protected]"                                         \
    "Backup Server Down" "The backup server is down."
fi

It just notifies me when a server has a power outage and needs my intervention for decrypting and mounting its drives.

It just notifies me when a server has a power outage and needs my intervention for decrypting and mounting its drives.

or when a server is unreachable.