New Feature: Restrict who can use the SMTP Relay

We've launched a new feature that allows you to restrict who can use the SMTP service by From Address. Under Settings --> Advanced --> From Addresses, you may designate which email addresses and domains can send through the relay.

By default, all email addresses and domains can send through the relay.

You only need to specify From Addresses if you wish to restrict the relay to use just by certain people. If you wish to restrict the use of the relay to an entire domain, you can use the wildcard notation *@domain.com as the From Address to represent all addresses for domain.com.

Note: Specifying From Address restrictions only apply to emails sent through the SMTP relay, and not through the transactional email API.