send a message to Mailgun

message-to-Mailgun.bash

#!/bin/bash

# default
if [ -z ${CURL+x} ]; then
    CURL="/usr/bin/curl"   
fi

# mg_domain, api_key, MSG_SUBJ_PREFIX, MSG_FROM_EMAIL, & CURL if necessary
CONF="${HOME}/.Mailgun.conf"
source ${CONF}

if [ -z ${to_email+x} ]; then
    to_email="${1}"
fi

if [ -z ${MSG_SUBJ_PREFIX+x} ]; then
    MSG_SUBJ_PREFIX=""
fi

if [ -z ${subject+x} ]; then
    subject="${MSG_SUBJ_PREFIX}${2}"
fi

if [ -z ${text+x} ]; then
    text="${3}"
fi

if [ -z "${4}" ]; then
    from_email="${MSG_FROM_EMAIL}"
else
    from_email="${4}"
fi

${CURL} -s --user "api:${api_key}" \
    https://api.mailgun.net/v3/${mg_domain}/messages \
    -F from="${from_email}" \
    -F to="${to_email}" \
    -F subject="${subject}" \
    -F text="${text}"