On first boot TurnKey asks for your email address in the security alerts dialog. If you're launching TurnKey from the Hub this email address is preseeded from your account's email address.
This email address is used to:
Alert you when automatic security updates are installed to your system.
Alert you when monit, the embedded monitoring system, detects RAM, CPU and HDD limits have been exceeded (RAM = 75%, CPU = 90%, HDD = 90%)
Send a subscription request to the "Security and News Alerts" list if you aren't already subscribed.
The list is very low traffic, sending out only critical security alerts and up to one email a month with important announcements.
You will need to confirm your subscription by responding to the confirmation email. Afterwards, you can unsubscribe at any time.
Workaround for Email delivery issues
To maximize email delivery we recommend configuring your system to relay email to an established reliable email provider.
Why is this recommended?
By default email alerts are sent directly using a private internally accessible mail server (Postfix) embedded into your TurnKey system.
Unfortunately due to common spam protections these emails may not get through. For example Dynamic IPs often get blacklisted due to (previous) abuse by spammers.