'''Required:'''
* Open outbound ports 80 (HTTP), and 443 (HTTPS) to all sources.
* Open outbound port 22 (SSH) to all sourcesyour other SmartSimple environments (e.g. the prod environment) to allow them to sync with each other.
* Open outbound port 123 (NTP) to all sources.
* Open outbound port 587 (SMTP) to all sources.