CaptainCore 
Configures Gravity SMTP to use Mailgun via SMTP connection with a fallback option to send out PHP mailer.
// Changes the following variables
from_name="$( wp option get blogname )" # Email from
license="########################" # Gravity SMTP license key
mailgun_from="[email protected]" # Mailgun SMTP send from email
mailgun_user="[email protected]" # Mailgun SMTP username
mailgun_pass="######################" # Mailgun SMTP password
domain=$( wp option get home )
domain=${domain/http:\/\/www./} # removes http://www.
domain=${domain/https:\/\/www./} # removes https://www.
domain=${domain/http:\/\//} # removes https://
domain=${domain/https:\/\//} # removes http://
domain=$( echo $domain | awk '{$1=$1};1' ) # Trims whitespace
read -r -d '' gravitysmtp_config << heredoc
{"debug_log_enabled":"false","setup_wizard_should_display":"false","license_key":"$license","enabled_connector":{"generic":"true","phpmail":"true"},"primary_connector":{"generic":"true","phpmail":"false"},"backup_connector":{"generic":"false","phpmail":"true"}}
heredoc
read -r -d '' gravitysmtp_generic << heredoc
{"host":"smtp.mailgun.org","port":"587","auth":true,"username":"$mailgun_user","password":"$mailgun_pass","from_email":"$mailgun_from","force_from_email":true,"from_name":"$from_name","force_from_name":true,"encryption_type":"tls","auto_tls":true,"use_return_path":false,"activated":true,"configured":true,"enabled":true,"is_primary":true,"is_backup":false}
heredoc
read -r -d '' gravitysmtp_phpmail << heredoc
{"from_email":"wordpress@$domain","force_from_email":true,"from_name":"$from_name","force_from_name":true,"use_return_path":false,"activated":true,"configured":true,"enabled":true,"is_primary":false,"is_backup":true}
heredoc
wp option set gravitysmtp_config "$gravitysmtp_config"
wp option set gravitysmtp_generic "$gravitysmtp_generic"
wp option set gravitysmtp_phpmail "$gravitysmtp_phpmail"
wp plugin activate gravitysmtp
