Sendmail wrapper for mailgun

sendmail-mailgun

1583114700

If you use the `sendmail` linux CLI and you want to route outgoing emails
through mailgun, write this file, make it executable, and add it to your
path before the actual exectuable is found:

```bash
#!/bin/bash

# Shim for netdata to send emails through mailgun
# filename: sendmail
# suggested location: /usr/local/bin/

# Installation:
# 1.  Write the contents of this script to a file called "sendmail"
# 2.  Fill in the mailgun smtp email and password from https://app.mailgun.com/app/sending/domains/albertyw.com/credentials
# 3.  sed -i 's/SENDMAIL_PATH_REPLACE_ME/$(mailgun)/g' sendmail
# 4.  `chmod +x sendmail`
# 5.  `sudo mv -n sendmail /usr/local/bin`

SENDMAIL_PATH="SENDMAIL_PATH_REPLACE_ME"
MAILGUN_EMAIL="REPLACE_ME"
MAILGUN_PASSWORD="REPLACE_ME"

# shellcheck disable=SC2068
"$SENDMAIL_PATH" \
    -S smtp.mailgun.org \
    -au "$MAILGUN_EMAIL" \
    -ap "$MAILGUN_PASSWORD" \
    $@
```

Add note about sendmail mailgun
Add note about sendmail mailgun
